I don’t get this argument. “Here’s a legal document we wrote that says that you’re allowed to redistribute our code. But aside from it we’d like to you to not redistribute it on platforms we don’t like for whatever reason. But we won’t spell it out explicitly in the document itself because reasons, instead we’re guilt tripping everyone who does”.

I respect developers right to put any restrictions on the code they share with the world. But I believe it should either be explicit or not restricted at all. Either write the license that says exactly what you want or otherwise don’t shame people into the desired behavior.

Edit: one could even add a more generic statement to the license stating that it’s forbidden to share the code on any platform that would use it to train their AIs per their ToS, so you don’t need to single out GitHub and potentially others in the future.