Why does a man join a nudist group?

Answer 1

That's a pretty non-specific question.

A man may join a nudist group for many reasons.

He's single and looking for a life-partner of like minded lifestyle.
He's single, wants to stay single and simply enjoys being a nudist.
He's a bit of a perve and and has voyeur traits.
He's single and never experienced the nudist lifestyle before so wants to try it out in a social atmosphere.
He's in a relationship however his partner is not a nudist so he seeks friendship of other nudists.
He's in a relationship however his partner works so much they can never make  the time to spend together at such venues.

etc...
etc...
etc...
Yes, there certainly would be some single men who join for reasons, not quite so pure and non-carnal.
Yes, there certainly would be some single men who join for purely platonic reasons.

It's just a fact of life with nudist venues.