[Hack]

Aggressively yes. Obviously he should bet and if he's called to the river and not raised he should stick with it, but the chances of spiking a King on the turn is 22:1 I think. Obviously he will get paid off big if it does hit but it just doesn't happen that often. It's also quite possible that one of his opponents has a King as well, which decreases his outs to one, basically. But we can assume that he has two outs.

I am just speaking from experience that playing weak Kings and weak Aces is popular.

I think his hand here is beat more often than not, and while he has to push it since he bet before the flop, I think that Kings are probably -EV against 5 opponents in a raised pot when an ace hits the flop, even considering the chances of spiking a king on the turn or river.

Being behind here 80% of the time is hardly every profitable, even as like I said, you consider the possibility of spiking a king on the turn or river. If he is raised, however, it's an absolute fold, no question about it.