Hypothetically speaking in a scenario where Parker is the captain and everything else is held the same. Parker, recognizing their dire situation and given his weak health, decided under his own volition to sacrifice his body so the other three men could live. But he would need them to murder him because his religion strictly forbids suicide (his own interpretation of his religion would not consider consenting to his own murder as suicide).

Could this murder be considered justified by necessity?

Does this hypothetical scenario weaken their morality argument? Allowing this excuse to murder, law and morality will not be divorced. Parker is performing his moral duty to his crew by sacrificing himself.

OR.... Do I need to go study more?....I am going to go study.