This is part of a larger question in the progressive community over whether to share stages with the likes of Breitbart, or whether to appear on Fox News, or what have you. Some argue that they should not allow the lies of a Brietbart or a Fox to go unchecked, and that progressive voices have to be heard in those venues. Others think that no progressive should de facto legitimize a Breitbart or a Fox News. This was the argument behind the ultimately successful boycott by Democratic candidates of a 2008 Fox News Presidential primary debate.
I think the debate gets a little too intense sometimes, but in this case, with ABC dealing with their own self-inflicted drowning, I would see no reason to hand them a lifeline and a way out of it. Let them have their little Breitbart show, and I will enjoy checking the ratings the day afterwards.