While I definitely think that video games should never be used as a babysitter or parental substitute, I don't think that shooters are terrible influences for children given that the correct parental controls are put in place and the child in question is mature enough. I've been playing Halo since I was 10 and I've never displayed the aggressive or antisocial behaviors you listed; same for my friend who has been playing since he was 8 (he even became an Eagle Scout, a considerable honor).