From the photo, it looks as though you had a funeral director sitting next to you.
I don't think you helped your position by trying to tell the individual how he should act, according to your personal codification of onboard rules of behaviour.
Simply asking him to make more (shared) space available for you, or taking it over when you had the opportunity, might have been better than initiating a vaguely passive-agressive rebuke by telling him he was infringing unwritten rules of frequent travellers.
Attempting to involve cabin crew in your conflict, then taking a photograph of his arm on the armrest, probably convinced him he was safer ignoring you.
How was your window-seated neighbour?