The point being made is that the "for free" part of that sentence doesn't actually exist in the GPL. You can modify GPL code, then charge for access if you want (which, IIUC, Red Hat does). You just have to give it to whoever you sell it to under the terms of the GPL, which means your customers could give it away for free if they so choose.

    > which means your customers could give it away for free if they so choose 

If you’re only guaranteed one sale before your first customer undercuts you, then it is free “in the limit”. That is why Red Hat sells everything ancillary to the software itself (quality assurance, training, documentation, support, etc.)

ChessBase is selling the software, and they aren’t getting undercut because they are not redistributing everything the customer needs to rebuild it from source. It will be interesting to find out what that is (neural net weights, or whatever) and whether the court upholds that this is not copylefted under the GPL.