Yes, the hip displacement and especially the verb used for it is the biggest issue for that reading.
For the verb, I know a microscopic amount of Hebrew compared to Alter, but I wonder why he thinks it specifically means a light touch. It’s commonly used in legal texts to say how people become unclean by touching the wrong things. Those texts don’t just forbid light touches as if rough handling of forbidden matter was okay! It just seems to be a general word for touch – any kind of contact, light or hard, brief or sustained.
Given how the man does this move after a long time wrestling without being able to get the advantage, I think we’re supposed to read it as some kind of underhanded move, maybe even a trick. Last time Jacob grabbed his heel; this time he hits Jacob’s hip. (Perhaps he sets Jacob up to lunge at him, then pivots to push his hip, throwing Jacob off-balance as his lunge sends him crashing down on his [other?] hip.) The text seems to describe a two-part sequence of Jacob’s hip first being touched, then dislocated in the tussle.
Anyway, the text is so spare it’s all just guesses, and I can’t speak to the Hebrew. I do agree that a magic touch of some sort would also fit, which would suggest at least an angelic combatant. But since the reason for the move is to get away before daybreak, I really don’t think this fits for God (or even an angel). I can see why some suggest a demon, but that doesn’t fit so many other details.
As far as what makes the story the most dramatic and what best develops the themes already in play, I think the twins wrestling far eclipses other readings. In particular, any readings where his opponent is just playing around rather than using his full strength really deflate the energy of the story. If he could win at any time, then like any deus ex machina, it’s a bit of a letdown.