Here Beatty offers Guy a chance to burn down his own house, which--as we've seen--has been targeted for destruction because of Guy's "subversive" behavior. As Guy grips the flamethrower in his hands, Beatty mocks Guy for being a "burden" and suggests that he'll enjoy burning Guy to a crisp.
It's not a great idea to antagonize someone with access to a working flamethrower. But perhaps Beatty's behavior in this passage is indicative of a broader problem with his society. On some level, Beatty seems to want Guy to attack him with the flamethrower (which Guy does immediately after this passage)…