I see it as a distinct possibility. It appears the fire was allowed to burn for around two hours before any water was poured on it, though the room did torch up pretty quick. Also, there were large traces of ethanol found where the garbage can was, and Maher said it was half full, and he states that it could of already contained soiled/soaked items.
Also, according to Ted Maher's statements, he already injected himself with Lidocaine and cut himself by this time and run around acting like he'd been assaulted, so I suspect he was a bit woozy by the time the fire was started and could of spilled something in the can or on the floor as well. One would have to admit the way he describes it he wasn't quite thinking straight.
If we light a fire in your garbage can at home and go to the movies for two hours, I wonder what's left when we get back.