That'd be the time to abandon Bitcoin for good. The day mining pools reorg the chain is the day there is nothing valuable to secure. It'd be suicidal.
No pool would really want to do that because they would probably see the same things and know that it would kill their business.
Would it, though? That'll be the day the likes of us abandon bitcoin, but the masses don't care. They let centralized exchanges act as banks, surveil their every move, hold their coins, and dictate how they can spend them. They use custodial wallets which can stop serving them at any time, like Wallet of Satoshi just did. All they care about is "when moon", and not at all about the whole point of bitcoin in the first place. They cheer for more regulations since it means bitcoin "is going mainstream", and eagerly await institutional investors, ETFs, and the like. Are they going to care about a few transactions belonging to other people are being censored? The fact that this censorship is barely being discussed across this forum/Reddit/Twitter/etc. tells you all you need to know. People don't care.
In that case, it would be better to have established some sort of organization to be able to in a way punish the bad faith miners by responding accordingly in a timely manner.
So a centralized third party to police the other centralized third parties? No thanks. What we need is more privacy by default on the base layer to make this kind of censorship impossible to begin with.