Wicked, I say that if he like them and it is NOT causing anyone else harm, let him wear them. As I have said in a previous response, they sell mens underwear that is made of silk and the same material as ladies panties. He can buy these and I would think he could feel the same. I have worn these for several years since I had the hot cotton briefs being sold for men. Plus there are too tight for the most part. I tried my wifes on before and didn't like the cut of them, so I found what I liked in the sears and or penneys catalog.
If that guy is like yours and is visiting bars and circling personnals and answering ads and using a different screen name on the computer, I would think you and any woman has rhe reason to worry.