V.W.
Bottom line would seem to me to be that you need to find out why they hold that tenant. WHY is that a requirement? Not for you to try to change it, but so that you understand why it matters to them. If you don't agree that it matters, or believe the same things they do regarding baptism, then you might revisit why you want to be part of their congregation in the first place.
It would seem only logical that to want to belong to a church, you would want to hold fast to the same beliefs. And if you do not believe the same things, then why would you want to be a member there? I would think you would want to find a church that holds to the same beliefs that you have.
I can certainly understand why your husband is uninterested to being baptized again, given what the Catholic faith says regarding baptism. But the bigger question for me, would be, why as a non-practicing Catholic, that seems to still hold the Catholic faith regarding baptism, would he want to belong to/attend/participate in a church that requires its members to do something he doesn't believe in?