Oof. This is rough all over. I definitely don’t think that OP did anything wrong, however, cabin crews’ spidey senses are already tingling when in charge of a UM since if anything were to happen on their watch they would end up on the news.

I once ended up next to a UM (F~12yo) on a short haul flight and immediately asked if “I would be less in the way if I sat somewhere else”. I was thanked and ended up in a rearward middle seat for two hours.