"You have a right to drink, but you do not have a right to do whatever it was you were doing. There are places for such." Zoe didn't get into details, and she'd tell him exactly where he could go if he ever mentioned that imaginary friend of his. An overactive imagination could be very gorram annoying, especially when it led to someone yelling about getting undressed.
"Now, apologize. I'm not asking." She hadn't moved toward him; she hadn't clenched her fists in anger. She'd simply stood there, but even standing there she might look as if she were ready to see him right out the bar and onto the street. In the past, she might have let it go, but there was something very unappreciated about what he had said to her. Or to the place in general. It didn't matter. She wasn't going to stand there and listen to it, nor was she going to have someone like that in a public place. He was obviously unhinged.
The bartender really didn't like what was going on. He was definitely considering calling the cops. He didn't need this sort of trouble. He didn't even think what Gaius had said was all that bad, or not bad enough to get upset over, but he really didn't know how volatile the woman was.