All about opinions, I’m going with mine and Chris Hughton’s, he should have walked and if it was an Albion defender who’d done that he would have, I am absolutely certain on that last bit
I thought, though I may be wrong, that you get a red for intent. Looks like red card to me
https://www.thesun.co.uk/video/football/man-city-star-kyle-walker-dodges-red-card-after-var-review-over-headbutt-against-brighton/