Thing is, the whole point is that, if she would react that way, then they shouldn’t be married. If he can’t tell her about this concern, how is he going to be able to tell her about other problems in the marriage that will inevitably happen?
Problem is, if she is a good person but also strongly disagrees, will this also create resentment? Will she be able to be happy without this one last hurrah? Would he be able to be happy if she goes ahead? It’s very possible that they won’t. But, really, they’re no worse off than when they started.
Going from my own martial experience, I went with voice misgivings but do not ask her to give it up.
Given how early in the marriage this situation is happening, it is especially important to discuss these sorts of things. It establishes a pattern of communication that will hopefully continue throughout the relationship. if he does not talk about it, how will she ever know how he feels about things? And how will she know what he is really upset about as it comes out in other ways? From my own standpoint, I’d be pissed as hel if I found out after the fact that my husband had strong unexpressed feelings about some action I took that may have done unintentional material damage to the relationship. After 20 years of marriage I have a pretty good idea of how he will feel about things, but 2 years in? Not so much.
When things like this came up(not the nude stuff - nobody ever asked either of us to do that, sadly), we established a pattern of discussion wherein both parties had the opportunity to make feelings known without anyone saying please don’t do that. If it was really important to the party to continue with the course of action, at least they were doing it knowing the score and had the opportunity to express why it was important enough to risk upsetting the other partner.
Sure, it led to some fairly loud discussions early on, but it also helped establish boundaries, priorities and expectations.