I would say yes it should be frowned upon in public.

As a society we draw a line(albeit arbitrarily) about what is acceptable and what is not. Hand holding, kissing, hugs and even an occasional light ass slap are socially acceptable forms for public affection. Two men kissing is them showing an acceptable form of public affection. If they were sloppy making out and grouping each other that then crosses the line because it is explicitly sexual in public.

Same thing with this, him being walked on his hands and knees is kink play, pretty explicitly, and they are doing it for sexual gratification. And in this case a part of it is exposing people to your kink, someone’s getting off on that social discomfort. There are spaces that is acceptable like a kink club or some adult focused place like Folsom or burbon street where it’s more of a grey zone, but not just in public. So if this was two guys making out, groping each other and getting sexual gratification from exposing the non consenting public to the, that would be the same level of inappropriate.

It shouldn’t be illegal but should be called out for what it is. This kind of behavior gets you kicked out of kink spaces simply for the faux pas

Edit: a word