The only obstacle I would see P-3 guys having getting a commercial job would be less PIC time with three pilots on every flight.
But then P-3 missions are longer than fighter missions are they not? A lot longer. Most of it at low altitude too.
IIRC, wasn't it the case with some of the majors that military pilots were given a formula to compute total flight time? I am almost certain that dh's hours increased because certain airlines weighed military hours higher than civilian flight time?