I'm 26 and I love panty shots. I don't think half their audience is male and over 20. I think that the international audience is probably older. As a Japanese exchange student once told me in broken English "You watch Sailor Moon? In Japan that is a show for little girls.". Well it kind of is here too.
Your friend must have never seen the wide varety of "adult" Sailor Moon products on the market in Japan - condoms, sex toys, fetish gear, etc. When I was in Japan back in '98 I found a machine in a public restroom that sold the condoms and I cleaned the sucker out trying to get a complete set. Got every one except Sailor Mars. Every other machine I ever saw was sold out.