I wouldn't say it is quite the same threat model, but certainly a powerful attack vector if you happen to control 1/3+ of the voting power. In the unlikely even

I wouldn't say it is quite the same threat model, but certainly a powerful attack vector if you happen to control 1/3+ of the voting power. In the unlikely event that someone does compromise 1/3+ of the voting power, the remaining validators can always hard fork to a new quorum, though this is an expensive and highly synchronized affair.