It should also be pointed out, everyone thinks Voldemort is dead. Remember what happened in Order of the Phoenix to everyone who was spreading the bad news? That’s more likely to be met by confusion than by bargaining.
He doesn’t know about the horcruxes. He may suspect that Harry is Voldemort, but Harry doesn’t know that, and thus has little reason to think that Lucius would believe him either. For the most part, the Death Eaters are as convinced as anyone that Voldemort is dead.
It should also be pointed out, everyone thinks Voldemort is dead. Remember what happened in Order of the Phoenix to everyone who was spreading the bad news? That’s more likely to be met by confusion than by bargaining.
Lucius, on the other hand, does know...
He doesn’t know about the horcruxes. He may suspect that Harry is Voldemort, but Harry doesn’t know that, and thus has little reason to think that Lucius would believe him either. For the most part, the Death Eaters are as convinced as anyone that Voldemort is dead.