Good point. Contrary to what Nicky said, Thibeault did state some reasons. He stated that under Layton there was more emphasis on positive politics but that under the current NDP leadership it is about partisianship and vicious attacks. (And just look at the way NDPers attack Liberals on Babble). What happened to love is better than hate?
Btw, I guess Nicky missed Thibeault's interview on Evan Solomon last month. Thibeault said he'd been having issues with the NDP leadership for some time, and that Mulcair's recent impulsive idea to re-open the gun registry was something else he had a problem with.