Censorship resistance & UASF

If large validators like Coinbase decide to enforce some OFAC measures and censor some transactions within a block, then we could see a User Activated Soft Fork (UASF) to burn such validators.

How this would be done in practice? Also, is it risky / centralized to use MEV-Boost as Flashbots / other MEV relayers & searchers could also decide to censor some transactions?