Well, it's no fun if they're not fighting back. Especially since Spike has no reason to really beat up on this guy except a vague self-defense claim. Not that he cares much about that. "...never met her." It's clear he was thinking before answering. If he's met this Charlie, he does not remember.

Mercifully, no more punches come although Spike is ready if he needs to. The other isn't threatening to kill him still, which also helps. "You still gonna try and kill me?"