They are probably just used as a prop used to "break the ice" with potential 4th and 5th grade girls in public restrooms.
I am sure his fantasy involves his penis somehow while 'training' these young bathroom-stall first-time bleeders. Perhaps something like "you have to be opened up to be able to fit this new tampon. Come sit on THIS, all first time girls do!" or some equally fucking repellent shit like this.My best guess would be that the scenario is just masturbation fuel for him. He may or may not masturbate with the pads or tampons themselves, but I think its more the feeling of being that intimate with that aspect of womanhood that turns him on, hence the lying about being intersex etc.