Really, why should he not be allowed? I understand that football players often become role models for children, and I absolutely detest what he did, but the dude served his time and has been dealt his punishment. Why should we keep punishing him and keep punishing him? He's been out of the league two years now- due to jail time, no less- let him work his own way back in. I'm an animal lover, especially of dogs (I have four of my own), but Vick has been accused, tried, and sentenced. He's finished with his sentence now, let him get past it.
Seriously, how would you feel if you'd been arrested for statutory rape or some other sex crime, and you got insults and punishment everywhere you went? You wouldn't say to yourself, "I deserve that," you'd say, "I've faced my punishment, I'm not going to do it again, let it go." As cruel of an act as he's committed, he's still human, and we have to empathize at least a little.