If A ever acted like that towards me and my backpack I would tell him in no uncertain language to F' off. And if it goes on call the FA and have it explained he is out of place. I travel with only a backpack., and my single carry on is entiltled to go in the bin. I am not about to gatecheck my backpack because A thinks his dumb as rollar is more important.

B is also wrong. One can put A SINGLE BAG up overhead (with some defined exceptions). Small F cabins can fill up fairly easily with the space used for equipment/FAs and the bulkhead. Placing 2 or 3 items up top may not be prevented by the FA, but it is wrong. If the bins do not fill up, can always put something up top later.