Do people who celebrate this as a win for Nostr understand that Nostr relay operators don't have any kind of immunity whatsoever?

Unless we get King Charles the III himself to run a relay (he does have immunity, in the UK, in his other Kingdoms and also pretty much anywhere fucking else as a diplomat), which would be quite cool indeed (even to someone like me, who's neither a monarchist nor a British), relay operators are still subject to the law.

I do get Nostr is so irrelevant at this point that governments can't possibly be bothered to give a shit about it (nor can almost anyone else). Still not a win.

Governments acting in illiberal ways is not a good thing for anyone.