I think Obama welcomes attacks from the radical left. It makes him seem moderate by comparison. This way he can point to criticizm from the right and the left and claim to be in the middle. It's a variation on Clinton's Sister Souljah criticizm. This is Dick Morris triangulation. I wouldn't be surprised if Bill Ayers doesn't express his disappointment in how Obama has been governing from the center.
A lot of political propaganda is below the radar. The best sting operation is the one where the victim never knows he was cheated.