According to the linked article as well, so does Justin (and David McGuinty, as well):
Though Liberal MP John McKay (Scarborough Guildwood, Ont.) had at the start of the meeting waved a sheaf of delaying amendment motions he said was ready to move, he told The Hill Times after the meeting that Mr. Trudeau and Mr. McGuinty have said they wish to appear to respond to the Conservatives, and that he had only proposed a motion to have the appearances take place “forthwith.”The fact that both are willing to appear before the committee "forthwith" signals that they're willing to play the Conservative's games. It makes sense, because what can Calkins and his cronies really do - ask them why they said such things? Maybe they'll rile up the Alberta base again, but the novelty has passed, and now you've given them the chance to explain exactly why they said the things they did. That is the worst possible thing you can do in politics - give your opponents a chance to explain themselves, instead of wrapping them up in quick soundbites.
Mr. McKay said the Conservatives defeated that amendment.
“Both Justin and David said, ‘Oh, we would like to actually be here.’ So, if the committee wishes to donate two hours of its valuable time doing non-committee work, then certainly Justin and David are up for it,” Mr. McKay said. “The Conservatives didn’t want it forthwith, so they voted against the amendment for forthwith, and left the motion as is.
By the way, kudos to John McKay for attempting to stifle their stupidity originally. If there is one thing you can say about our remaining Liberal MPs, its that they're damn resourceful when need be.