Generally no, there is no excuse for a business to be rude. In reading just this one sentence from the OP, though, I'd say there's probably a whole lot more to it and the dealer probably had every right to be rude. That said, I don't read anywhere the the dealer was rude, only that they asked him to leave.
"So I storm off calling her a lesbian and telling everyone she will burn in hell."
Yeah, I'd ask him to leave as well and he'd be glad he did because after that, I would not be asking but indeed he would be leaving.
