That is not a request. That's a random announcement to me. Like me saying "I'd love to eat a pie."
Just because I announced this, you are not going to jump up to bake me a pie, right?
You don't have to do anything about random announcements.
Voyeurism is NOT a requirement in polyamory. It's a thing of its own. Some people want polyamory only. Some people want voyeuring. Some people want both. Some people want neither.
Even the whole neighborhood was doing it? Your consent to participate in things or not belongs to YOU. If he ever does make an actual request? You can tell your husband "No, thanks. Won't be doing that" if that isn't your thing.
Additionally a 3 people activity where you husband watches you share sex with your partner requires a 3 people yes. So even two people vote "yes" and one person votes "no" it is just not happening with that group of people.
- You and husband vote yes, partner votes no? Not happening.
- You and partner vote yes, husband votes no? Not happening.
- Husband and partner vote yes, you vote no? Not happening.
Besides, your relationship with your partner is between you and your partner. It's not to entertain your husband or get him off.
Galagirl