They want to shoulder the load: replacement is the goal. Why send your PRs to an open repo and have to deal with public review when you can push people to switch to a repo you control, with the ability to both block changes you disapprove of and force through changes you like? The technical and economic disagreements are a useful justification, but they're not the fundamental motivation.

You mean cryptographically signed proof that you've evicted the censor that used to live in your own head?

Annoying you is the goal. Goading your enemies into becoming emotional and making mistakes is a classic tactic.