> An attacker would not release a chain until they are certain to profit from it.
There are two scenarios: If they release a new chain after they have released a previous signature, their entire deposit gets slashed in both chains. If instead they withhold all chains then this would only work if they are able to mine multiple blocks in quick succession on different chains (since they would lose the opportunity to validate a block within the timeout window) and this is exactly equivalent to a POW selfish mining attack.
Right, and there are many variants of this scenario that other people can think of. It all stems from the same basic problems above. Punishing cheaters is necessary, but not necessarily sufficient.
The difference from a PoW model is that when mining is essentially free the incentives are different. If it doesn't cost you anything to try it makes game theoretical sense to do it speculatively.
There are two scenarios: If they release a new chain after they have released a previous signature, their entire deposit gets slashed in both chains. If instead they withhold all chains then this would only work if they are able to mine multiple blocks in quick succession on different chains (since they would lose the opportunity to validate a block within the timeout window) and this is exactly equivalent to a POW selfish mining attack.