Without any prejudice:
axiom: when you enter the plane, you have to follow the crew orders
flashback #1: guy stands in the corner, playing, not reacting to repetitive orders of the crew
solution: the guy gets kicked out
If I was standing in the back on the plane talking on the phone, and telling the crew that I only need 2-3 minutes extra, and they kicked me out for that - there would not be any discussion whatsoever.
Bottom point is: if a cabin crew member orders you to do something (sit down) - you sit down.
But this is of course only my very humble POV...