Well, yes it is weird, and then again no it's not. Jonathan's fetishes are based around what's forbidden, out of bounds, can only be accessed by a particular few. Women's loo? Forbidden to men. Menstruation? It's almost taboo for even women to talk about amongst themselves. Tweens and teens? Doesn't get more forbidden than that. Calling himself a Cimorelli sibling? It doesn't cross the line so much as nuking it from space. Women who are forbidden by culture/religion from handling his micropenis? He takes them to court. If it's a place he can't go, he wants in. Something he can't have will be fucking wrecked. Show him a line, he'll record Elmo talking dirty to a young girl.
A tampon is a double taboo; it's both a product of menstruation and an item that penetrates and is held within the vagina. It's actually quite simple. It's fucked up, but it's simple.