I have to go a little against the grain here - a lot of folks have offered that perhaps they didn't understand that the gathering was truly "women only". I do agree with that statement and I will say that if I was asked to host a gathering where my husband would be banished to a section of his own home and considered rude for merely existing in our presence, my response would be to politely decline hosting and remove myself from the group.
I get that some couples like to have their alone time away from one another and we certainly do too, but telling members of a household that they must make themselves scarce, even for just one day, is to me an incredible overstepping of boundaries.
Mentioning to Amy that you'd like it to be women only is okay, but be prepared that she may decline to host in the future if she truly understands that you don't want her husband present -- that is certainly what I would do.
Regarding the bolded, that's exactly the point. If Amy doesn't feel comfortable with the way the group has agreed to do things, then she is perfectly within her rights to bow out. No harm no foul. I wouldn't hold it against her any more than I would a former member who dropped out because she was returning to school and no longer had time for the group.
In a social situation where you are not able or willing to follow the rules, it's perfectly ok to drop out of the group. I just don't see how it's ok to deliberately not follow the rules. I don't blame you or her or her husband for not liking the rules. I do find fault with deliberately flouting them.
that what happened was that Amy sprung it on her husband that day or shortly before and that when he refused to comply it was too late for her to do anything about it. If this is the case, maybe it won't come up again as they will have had several months to get used to the idea. I like gellchom's suggestion that if he was really stuck there because of the computer, he could have worn earphones.
The fact that he deliberately made his presence known throughout the evening is what completely changed the dynamic for me.
To clarify a bit, bunco is played at three separate tables, usually in separate rooms and after each round people switch tables. So in this case, we were in the breakfast room, the dining room and the family room. Passing through the kitchen as we switch tables is a given. That's where the food and drink are plus it's the shortest route between two of the tables.