I'll just pop a slightly shortened version of the discussion from the other thread, and im happy to be told I'm wrong, assuming there's evidence of that.
A terms of service is legal agreement between two parties, the server and the user in this case. The user must (in most cases) explicitly agree to that agreement for it to be binding. A ToS can suggest implicit binding, but that's unlikely to be legally "fair". But that's irrelevant in this case as the ToS for lemmy.world did not have that in. Signing up to the server for lemmy.world requires stating agreement of this ToS.
A remote user has no sight of this agreement - it's not presented to them, and they have not accepted it. There is every chance they are totally unaware it even exists. Therefore they cannot be bound by that ToS in the same way you can't be bound to a legal contract you haven't seen or signed or agreed to. The only ToS that user has seen is their local instance ToS, assuming one exists.
So for the lemmy.world admin to ban a remote user because something about the remote user's account violates the lemmy.world ToS is unfair - that remote user is not bound by the lemmy.world ToS as they haven't got any legal agreement with lemmy.world.
If the precedent set was that the remote user is liable under lemmy.worlds ToS, then every single user would suddenly be liable under every single federated servers ToS and have a legal arrangement with every server.
My annoyance with the situation is the lemmy.world admins brandishing their ToS in this way. They can ban someone for any reason if they want, its their server, but to claim a ToS violation is, imo, absolutely not right as the ToS does not apply to remote users.
/rant
Edit: I think I find the argument that lemmy.world don't want to be in legal trouble also frustrating. It's disingenuous. Lemm.ee bears the legal responsibility for the user, none of that is passed on to lemmy.world. If the user was to see NSFW content on lemmy.world - ah, but they haven't. They've seen the content on lemm.ee. sure, it might be a lemmy.world community, but that doesn't matter, because that content the user is seeing is via lemm.ee, on a copy of a community, and so the lemm.ee ToS applies and has nothing to do with lemmy.world.
They've just decided to ban someone for being under 18 even though it doesn't affect them in the slightest.
Edit 2: sorry, I didn't even answer the question. IANAL but no, you can't be forced to accept a legal contract you've not seen and so they don't apply to remote instances.