If the engineers know it is not ready and they still deploy it despite knowing it is reasonably foreseeable that this system will cause injury or death, that is still on them. Unless the product/marketing people are holding the engineers at gun point, the engineers are free to refuse and quit if need be. I have quit jobs (with no prospects lined up) and turned down offers in the past due to ethical objections, so I am not particularly sympathetic to the "just doing my job" defense.