I know he brought it up, but you are the resident authority on things to know about the nudist culture, well you and Anudist maybe, so I posed my question to you.
I thought that since erections are a natural occurance and they come and go, perhaps not worrying about them with a towel would be a more natural way to deal with them. Of course this brings the question to my mind that maybe there are men who do like to show off their erections and so then it becomes a problem. That would indicate that there are undesirables among the nudist crowd. I suppose this happens frequently, hense the need for rules of etiquette.