After a few days of not eating, you'd eat just about anything. Even a weight lifter. It seems like a silly time to be worrying about meat quality, no offense.
I would take him out just because he's the only one that could really have a chance at getting the gun away from me, and that is what I would really be caring about in a situation like this one. Its not like I would be leaving the bullets in the gun all the time, though. I figure, when I slept, Id have them down my pants. Then, either the ladies, a very desperate man, or a gay man would come get them from me. In the case of the ladies, I would keep them down there. The other two, Id pistol whip them a few times to make sure they didnt do it again.
Without the weight lifter, we still have 7 MEN to do rowing. Besides, you have to row in unison otherwise it doesn't work as well. If he's going faster than everyone else, it doesnt do any good.
The nurse would be vital to survival, and if she has moral scruples about cannibalism, then guess who doesnt get to eat?
After the weight lifter, I would take out the hick. He's useless and annoying. The only reason I take out the weight lifter first is that he has the strength to wrestle the gun away from me, and he's more likely to be gay and want to get down my pants for the bullets. Haha, just kidding.
I disagree, though, with your philosophy about people being edgy after you killing someone. First off, you're the leader automatically because you have the gun and the authority from being an officer on the ship. Resorting to cannibalism probably wouldnt happen for AT LEAST 3 days. Everyone would be starving. I doubt anyone would agree with the choice of WHO to kill, but, since I have the gun, too bad, eh? I bet that would make SOME people edgy, but I personally think that it would make more people scared. If you kill someone for the reason of them being strong (of course you wont reveal that, but, its what they will assume) then I doubt anyone is going to mess with you after that, unless you are leading them in a real bad way.
Hopefully the weight lifter is large enough to last for a while, he should be pretty bulky and meaty. After that, you have the hick. If you're really hungry, then you move on to the cop. He's the next closest thing you have to authority (which you need to be the only form of) and hopefully not one of those gung-ho cops that like to take control of situations. Otherwise, you take him out second. He would be the only one to tell the authorities of what happend, besides the nurse.
Though, I do beleive it depends on where it happens for you to get charged with it in America. You'd more likely be charged with murder than cannibalism, Im pretty sure that only some states have a law against specifically cannibalism, but I could be wrong. In a situation like this, I dont know how likely you would be to be charged with anything.
Just my thoughts!