I'd prefer it if Apple didn't enter the moral policing world. Well, beyond their already no-porn policy. But then again, Americans always were prudes(puritans) by European standards.
I never said I was against it being in the store, but it just seems like the sort of thing they would have an objection with (simply to avoid the bad PR). They have banned many other apps for much less obvious reasons.
I'm not sure how much scrutiny regarding application function (as compared to a quick test of whether there is porn etc.) there is in the Apple approval process but this is little more than a calculator. In fact, as far as I can tell it doesn't necessarily have to be used for killing people (could be used for accuracy, for hunting, for physics tests who knows).
http://www.knightarmco.com/bulletflight/