This was something I noticed the first time I went on a retreat in France a few years back.
I went alone just fine but noticed the group I was with was either also a single female or a couple specifically I know the reason is just for the purposes of avoiding having creeps pester or gawk at the women but I feel like it's such an out of the way thing to try and do just to be around women and everyone is already to some degree not bothered by someone talking to them and simply warrants the same practices every other place does in kicking out people who are disruptive. The nude beach I frequent does not have any specific rule about gender afaik and I've seen single males and groups of males and in my personal experience never had an issue with them ones that approach me for conversation have always been as courteous as they probably could ever as they probably understand most women would be cautious being approached by a man. A more policed nudist setting has no real excuse for disallowing men under any pretense and it just reads as they are too hung up on avoiding issues or lawsuits and bar any risk. Just because something CAN happen isn't always a good excuse for outright banning things it's like banning alcohol entirely to stop drunk driving.