Consistency...

There are three things in this world that no one ever suspects: the Spanish Inquisition, the Cubs to win the World Series, or for rabid stuffed teddy bears to attack viciously with plastic silverware in the middle of the night. Especially if said household being attacked was devoid of children to possess homicidal bears wanting to kill everyone. Mortimer was incensed when he thought about how the bears were not only trying to kill him, but were breaking and entering to do so. It fueled his rage to where he'd had no compunction about blowing the stuffing out of them.