(THEORETICAL) Recruiters: Someone walks in, says he is terminally ill, and asks a for suicide mission (read)?

He would not be allowed in. The liability issues are severe and cannot be ignored. Even simply stating that you "want to kill people" is enough to keep you out. No commander in his right mind would ever admit that anything such as suicide missions exist, even though reality may tell us differently. The government would never invest the million+ dollars necessary to train him just for one mission.