A candidate polling at around 1% needs every attention he can get. But I doubt skipping a debate is the right thing to do.
This is only a move that does more good than harm for Huntsman. New Hampshire is his last stand and he's dropping. He needs to make it clear that he's their candidate and Romney isn't. If he can't win New Hampshire or place second, he can't contend anywhere. And he's not going to move up nationally any other way.
Why Gingrich, Bachmann, and Santorum said they'd boycott the caucus if it didn't change it's date I'm not sure why. The state is more favorable to Romney and Paul so it's a no brainer they wouldn't threaten it.
I'm not sure what Perry's stance is, but he's probably playing it safe staying out of this debate over Nevada and New Hampshire for as long as possible.