If it's contested, if forces and chain choice and a split that cannot be brought back together without another emergency intervention. So yes, effectively it is a hard fork by history change rather then a rule change. And if not Core, who and how? I think there are some very serious and committed...

"Their reputation is not deteriorated in the eyes of serious people" What an odd thing to say about people involved with Epstein who changed Bitcoin software for Citrea and spammers.

your simple checkpoint doesnt address the older nodes on the network from re-org risk which would be a forced upgrade. checkpoints to invalidate valid chain(s) of blocks would be a hard fork