I went back and reread the letter. LW says,
even though the wife prepares everything for her husband's meeting, she's told to slip out of the house before anyone arrives
To me that sounds like that's the arrangement the LW and her husband have not something the club founder has said. It sounds like in their house the wife is the one who does the preparing when guests are coming and now she's incensed that she is doing all this and not getting to stay while the meeting is going on.
Then she says,
My husband agrees that this is ridiculous and is considering quitting the club
Here's the conversation I imagine:
Husband: The men's club is coming over tonight. You'll need to prepare for them.
LW: But I don't want to leave the house. Organizer is a chauvinist.
Oh yeah, I agree, I could
quit the club but I've made friends with these guys. I feel bad about it but it's all the organizer's fault! He's got us bamboozled.
LW: Grumble grumble
Husband: Heh heh heh (evil laugh)
So yeah, I see this as a matter between husband and wife. She doesn't want to leave the house and he doesn't want to quit. In her place I'd probably just tell him to do his own "preparing", whatever that entails, and I'd go out and _______. (Fill in the blank with whatever you like to do. Shop, go to the movies, etc.)
ETA: Even though I alluded to this, I meant to say that "preparing" is what she says in the letter without expanding on what that actually entails. Could be a clean up from top to bottom and gourmet snacks or it could just mean making sure there are clean towels in the bathroom or whatever. So we don't actually know how much work is involved in "preparing".