I'm still on the side of rude, since he seems to have had at least some idea it was a ladies night only. I think the situation is different with one's children than a spouse, and that the spouse has some type of role in hosting since it's their house too. Greeting someone, asking if you can get them a drink or snack while you're in the kitchen or passing through is reasonable. Interjecting constantly, no, but if you are passing through and hear the discussion, I don't think a comment or two is out of line.
Speculating on the state of their marriage, comments that he was so territorial that the only thing he didn't do was piddle in the corner is, to me, over the top. He could be socially awkward or lonely. He could be abusive or controlling and not want to let her out of his sight. She could be abusive and controlling and not want to let him out of her sight, so he had to stay. She could have recently had an affair and he was concerned that it might be starting again, and thus listening in. We just don't know.
A reasonable thing to do is to talk to her, tell her than having her husband there changed the dynamic for the worse and that while you have no objection to seeing him at other times, Bunco night is meant to be women only. Make the comment about the rules of the night, not her husband.