I don't see a stipulation in the vows anywhere where it says it is ok that he shacks up with another woman and has kids with her just because his wife is ill. In fact, my wedding vows said through sickness and health. Adultery is the one sin that is acceptable grounds for divorce. MS broke his vows and therefore forfeited his rights.
Suppose my wife goes into a PVS and after a few years of treatment she doesn't improve. She has already told me doesn't want to be in Terri's state. So I pull the feeding tube and mourn for her. Five years later I meet another woman and we start a new life together.
Oh wait, I can't because "conservatives" have said I can't pull the plug without her family's approval.