Since you want to discuss moral ontology...
After an asteroid strike, there are two survivors in a specific area.
One of them, Fred, found a nice little oasis of greenery and a team of oxen, who miraculously escaped the conflagration. He homesteads this little patch. There are no other oases for miles around.
Beepop, the other survivor, straggles in, half starved to death, and lights upon Fred's little camp. He wants some food, but Fred tells him to go to hell.
Beepop decides he's good as dead in two days, so he eats his last remaining milky way bar and musters his remaining strength for a fight.
Fred, realizing his situation is precarious and not wanting to feed everyone who straggles in, gets ready to defend himself by killing Beepop, hoping the next straggler is less male.
They fight. Who is morally right?
Since you have a sound moral ontology that holds in all cases of conflict, and is true, you should be able to decide who is right.