Rumple hurting children was actually pretty taboo at one point.
I don’t think we’ve ever seen Rumple steal kids for any other reason than serving as a black market adoption agency, so this is new. Didn’t Zelena use baby Neal for a spell? And technically Snowing used Lily for the infamous darkness dump spell, right?
More abstractly, I’m under the impression that OUAT is trying to “reset” the B&B storyline to the pre-domesticated phase of the beast, and make Rumple scary/creepy again, but it’s not working very well because the writing for Rumple has been such crap in the last few seasons, and because it’s way too much retcon (though Bobby does do “emotionally tortured” so well I almost want to be convinced that he could pull it off). The dynamic in this scene reminds me a little bit of the French version of the B&B, with Vincent Cassel, where the beast really is a bit of a violent creep (though it’s Vincent Cassel, so you forgive him).