The attackers percentage of stake would obviously not change but all tokens on that entire chain would be worth nothing once the public realized it had been hac

The attackers percentage of stake would obviously not change but all tokens on that entire chain would be worth nothing once the public realized it had been hacked. They would hold 51%, or even 100% of a $0 token. All the verifiers who took part in the fraud and all the accounts linked to them would be traced and not given any stake in the new fork.