The statement is accurate, in addition to the basic Freeview lineup there's also additional content you can get with an internet connection on newer Freeview boxes and TVs. Some of it requires a subscription, but a lot of it is just more channels for free.
Personally, I don't like the idea of making changes that would force the removal of content for everyone by manually omitting any channels that Gracenote is providing as part of their lineups, if Gracenote is providing listings for it as part of the lineup, you should include it and leave it up to the end user to omit it. Not everyone uses Schedules Direct with a basic DVB-T tuner with no CAM where they only need get the unencrypted channels they can tune to with their homebrew DVR. Some are using it for the guide data to power software like TVG or other things like listings reminder widgets, other's are using it as a replacement of the poor BDS listings provided by Windows Media Center where they can use an IR blaster to control a settop box if they don't have a DVB-T tuner that supports subscription services. If people don't want to see those premium/subscription channels they can easily omit them on their end, either via their config file if they use tv_grab_sd_json or via their client, since if their client properly uses Schedule Direct's API it would only request listings for the channels they selected during setup. Things like the omission of subscription services, or any other channel for that matter, shouldn't be imposed on everyone because of a consensus, it should be treated no different than someone with Sky or Virgin omitting the Sports or Movies channels if they don't subscribe to Sky Sports, BT Sport or Sky Movies, or someone with only SD service omitting the HD channels.
I can count on one hand how many UK forum users have posted here since the shutdown of uk_rt and uk_atlas about lineup issues, so you're probably not going to get that many responses from people who had no problem so they had no reason to visit the website after they setup their account to file a ticket, let alone this forum, so they don't even know this thread exists. While people who don't want the channels listed can easily omit them, the people who would really be affected by a decision like this are those who want listings for those channels and they won't have any way to get them unless they add the lineup for another provider like Sky or Virgin to get listings for them, while any channels that are only available via IPTV won't be available at all. Maybe instead you can create an optional "no subscription services" flag that the client would need to send if they only want to get the unencrypted channels. (You could probably extend that flag to other countries as well since in many other parts of Europe it's common for encrypted services to be transmitted over the air so you can subscribe to additional content without the need for a cable, satellite or internet connection)
You also have to remember a lot of people came over from tv_grab_uk_rt and tv_grab_uk_atlas where you were able to select any channel possible via your config file and are still learning about everything Schedules Direct has to offer and how it works. The lineups provided by uk_rt and uk_atlas were just a guideline to make it easier to filter channels not on your platform, you could still manually add additional channels. The big difference some of them don't realize is that when a channel is removed from a lineup on Schedules Direct, it's removed for EVERYONE who selected that lineup, there is no ability for the end user to manually readd individual channels removed from their lineup.
Some people still don't realise that schedules direct is a lot more than the xmltv file you get from tv_grab_sd_json and you provide a lot more information than just a list of channel numbers and schedules. (i.e. many of the DVB lineups have tuning data in the maps which isn't collected by the xmltv grabber, developers of software that access the SD data directly can use it to avoid the need to scan or speed up the scanning process for their users by already defining which MUXs are used by that transmitting station) In time they'll realize what others who have been here since the day you started providing UK and other European listings have known. Like how much better the data is, like not having to use a reconciler to deal with the same show being called by different names (i.e. "Law & Order: SVU" vs "Law and Order SVU" or "Navy CIS" vs "NCIS") or channels that add "New" or "Marathon" or "Special" to the names of shows and being able to use the universal TMSIDs to keep track of series and movies, so the same TMSID and details for Game of Thrones on Sky Atlantic is shared with HBO in the USA, while the same TMSID and details for Doctor Who on BBC America is shared with BBC One.
In European countries, it's also common to be able to subscribe to additional channels directly via satellite without the need for a regular provider because of the common encryption system they use, so there is a need for lineups that includes both subscription and FTA channels. i.e. BBC Entertainment has a subscription service for select European countries. In Italy, not only is there the Mediaset Premium addon you can get via DVB-T complete with events you can order on a PPV basis, there's TivuSat which gives you a lineup similar to the DVB-T service, with the addition of some FTA European channels and the ability to add Mediaset Premium, you can also get Sky Italia which is also mixes in some FTA content. In Germany the most popular content is free to air on satellite, but with the same box you have the option to add additional services like Sky Deutschland, HD+ (which gives you the encrypted HD feeds of many of those FTA channels) and Viacom's MTV Unlimited which gives you the pan-European feeds of their music video channels like VH1 Classic and MTV Dance, while in Austria you can get ORF Digital, Sky and HD Austria. Even in the UK, with most satellite boxes you can manually add additional free to air content that isn't part of the regular Sky or Freesat lineup for your area, as well as in Ireland where a lot of the BBC and other UK free to air channels aren't included on Sky Ireland.
In the long term, it might be good to have an option to create a custom lineup, but considering how many channels are provided by Gracenote, it would be best to configure it on the web where you can search for channels and see a sample of listings for that channel before you add it, and not on the client level where you would need to download a list of tens of thousands of channels and keep on guessing until you have the listings for the feed you want (i.e. the Pan-European MTV Hits listings instead of the listings for the UK, Italian, Spanish or French feed), especially for satellite viewers in Europe where in addition to the multiple subscription services, you can also get tons of free to air services from multiple slots with a multi-LNB dish. (For reference, the IDs started at 10000 and now we're almost at the 100000 mark, with a bunch of gaps for channels that no longer exist)