I know there are a lot of Brian haters around here, but I think that Quagmire was in the wrong in the last minutes. Brian didn't know that was Quagmire's dad when he met her, and he was completely grossed out when he learned that. Quagmire just burst through the Griffins' house, beat up Brian within an inch of his life and threatened to blast Brian's head off if he came to his house, and walked away as if that would end anything.
If anything, Brian's final line was sweet, because, let's face it, Glenn deserved it.
But I'm probably in the wrong in thinking that. I'm wrong on a lot of things lately.