While I admit that's an interesting argument. . .I still say that after he's served his time he should be allowed to go back. . .but then again maybe not. . .
I'm not sure what 'action' humane organizations can take other than using their powers to draw attention to it, and sway opinion via finances and bad publicity. It is the NFL that gets to decide whether or not Vick can go back and more specifically the commissioner, Roger Goodell.
The fact that Vick committed a crime against legalized gambling and the system of organized is irrelevant to me. It's actually pretty irrelevant to the NFL too. (They only care if you bet on your own sport.)
More than 1 in 5 players on the NFL has been charged with at least one serious crime. That includes rapes, domestic violence, kidnapping, drunk driving (where an actual person was actually killed), murder, possession of illegal weapons and drugs.
There is no doubt that what Vick did was disgusting to say the very least but how is that worse than. . murder, repeated DUI's, kidnapping (that story goes along with the dometic violence), etc. Just because it was a crime against organized sports and he's an athlete doesn't mean it should be punished more harshly than manslaughter or rape. They are all serious but the NFL should do exactly what it has done in the past with other felons. . .which unfortunately has been to let them play. Or at least that was my original thought. . .
But as my dh and I were talking about this (because of course this would seriously change our fantasty football draft lists)

he pointed out something I hadn't realized and that is that Roger Goodell is new. He has not even been commissioner long enough to see 'real' games. And apparently he has kicked guys off of teams left and right for conduct that was 'unbecoming'. However, none of those guys have had prison sentences. . .which Vick will have when (and if) he's eligible. The NFL has also added a newer (or tougher) violent crimes clause in their contracts which has yet to be tested.
So what I'd like to see is consistency. If the NFL is no longer hiring felons despite their popularity then great. May he be banned for life along with any other player brazen enough to commit a crime. One thing is for sure, I won't be feeling badly for him either way.