The Carpetbagger asked this interseting question. Here's my answer:
The best thing to do would be to treat him according to option 2 and only treat him like option 1 to the extent he proves- not just appears- to be for real.
This doesn't mean you really treat him mean- quite the opposite, possibly. It just means that in your own heart you don't trust him. The best thing to do would be to keep him close until you can find out more about what he's up to. Let him think he has won you over. Don't let him really control or influence things. Spread doubt to his former friends, ambiguously, so they think he has in fact come over to your side and is giving you important confidences. If he's playing double-agent for the Republicans, make them worried so he becomes a more expensive double-agent- so they think they have to pay twice as much to be sure he'll be loyal. Even sacrifice, give up bits to him to win his confidence and make him think all the more he's won your confidence. Find whatever way you can to use him against the enemy and cast him adrift when you're done with him to live in the mercy of his (hopefully, effectively your) having burned his own bridges.
But this is in an ideal world. Actually, the typical liberal politician or activist is not nearly as cunning as the average punk maneuvering among his friends for respect or young woman maneuvering for romance. Your actions are going to show that you're respecting him, and it's too risky to try to tell fellow liberals or subordinates how to treat him because Republicans will want to know what you're all saying and thinking about this guy. You can't trust that other liberals will tacitly understand how to treat him, because they haven't learned this point of view from their experiences. They probably have other people around them telling them to forgive and forget and not scrutinize.
So you really just have to cut him loose and take comfort in the fact that if he's sincere, he deserves what may befall him because of what he did in the past. It really shouldn't be that way, and we should be able to conduct ourselves a smart way like I described above, but liberals really don't have it together to do that right now. Everybody wants to have their own opinion and too often the quality of that is equivalent to, trust a guy like Dowd as soon as he starts making some nice-person noises. Thanks for that enlightenment.
Right now, I'd barely trust your average bleeding-heart liberal activist to walk down the street holding the hand of my five-year-old daughter (if I had one) and not get gipped into selling her off to some child-molestor. I certainly wouldn't trust them around someone like Dowd.
Also check out my related comments here and here below this post.