If you're comfortable saying, I'm curious how this turned out for your friend and her stepsons. I know powerleveling is discouraged here, but there are various threads about real-life interactions with troons, and it would be germane to post this story there.
This might be controversial, but in my opinion, it's sexually abusive to steal clothing, and particularly sex toys, from a woman for the sake of a fetish, even if the woman in question never finds out about it. It would really not surprise me to learn that it correlated strongly with other sexually deviant behavior and violence against women or children. The "dark triad" or MacDonald triad has been mostly debunked, aside from the aspect involving torture of animals, but I wonder if stealing clothing from a mother figure for the purposes of sexual gratification in adolescence predicts future (sexual) criminality.