I was nice to David, I mentioned on thread that I started dating my ex-b while separated from my ex-H. I would never do it again (ever date someone while still legally married, even separated), but I understand how he feels.
I don't believe that we should be hard on those who come here from the flip side of the coin. I consider his being here in many ways to be a courtesy to you. You came looking for help here, and thus the 2x4's to help you keep on track (just like I get them). If Tony's W came here at his asking, would we pummel her? I wouldn't. Not even if she was struggling with the whole OM thing.
I am sure I've been too hard on a few people, but in this situation, I think it is best to tread carefully.
David did help others here as well. I just don't think there is anything gained by beating up on him. He KNOWS what he is doing. He knows in his head it isn't right. We don't have to accept it and say "oh, did you have a nice night with OW?" but we should treat him respectfully. If nothing else, do it for Pam. If we drive him away, it may hurt any chance she has with him.