A few more points.
First, cruelty to animals is a trait found in serial killers and other psychopaths. It's not normal behavior, and it's not something that a couple of years of therapy will change. It's not like being Catholic and going to confession, and all is forgiven. He was a torturer before, and he still is that today, even if he controls his impulses.
And while I can't read his mind, if someone does something awful and truly feels repentant about it, they do something to atone. I don't see him going to work to help abused animals.
I'm not saying he should rot in jail for life. He's done his time and that should be it as far as the law goes. But getting paid millions to throw a ball around is a privilege, and he does not deserve to return to a privileged station in life, either. Even more than what it says about Vick, I don't like what it says about our society that so many people are willing to brush over this just to get back to the game.
It sounds from initial reactions like a lot of Eagles fans are unhappy with this decision too... I hope they make their feelings known strongly, and I hope more people make the effort to reflect on the enormity of what Vick did, rather than dismissing it as "just dogfighting."