Since the public declaration by the officials is that public safety is their top concern while they announce plans to restrict access to assault style weapons, what is the real motive, as you say it is not to reduce deaths?
The felon cannot legally take possession of them, if his right to possess a firmarm has not been previously restored. Someone else can be designated to take possession, or the administrator/executor of the estate can choose to turn them over to the local authorities. That would be the choice of the estate though - and not a seizure. If for some reason the felon did take possession of the firearm(s), he would be committing a crime, which would happen to be a felony also.