Is Montag justified for killing Beatty?

I think Montag understands that this is what Beatty wants. Beatty lectures Montag on the dangers of books. He chides and threatens Montag who has a flame thrower. Beatty asks why Montag felt the need to keep books. Beatty is in an emotionally excruciating existential crises. Beatty loves what he is supposed to hate: he loves books but despises them at the same time. His whole identity is fragmented. It's quite possible Beatty knows his society is ending and he wants to die with it. Beatty threatens both Montag and Faber and then taunts Montag to use the flame thrower on him. Montag had little choice but to kill Beatty.