That's some sick **** fatman, way to blame the victim. Kid shouldn't have chosen to be gay, right? Or fat, kids certainly shouldn't choose that, and if they do I guess they deserve whatever punishment bullies want to give, gluttony is a sin, after all. While we're at it, better not choose to be poor, or anything else that sets you apart from the masses. Or you're just asking for it. Let's just blame the ones being tormented, that sounds fair, they should've just chosen to be normal and fit in so that normal people would like them.
Exclusion can certainly be bullying. When everybody gave out Valentine's cards in class, you had to give them to everyone, even people you didn't like. If your going to hang out with three of your friends that's fine, do that, but if you're going to want everyone at your party it has to be everyone.
Acceptance isn't about liking someone, it's about treating them like a person even if you don't like them. Parents and teachers cannot make kids like other kids, but they certainly can enforce rules about how kids treat people and attempt to teach them why it's vital that they treat people with decency.