I had no obligations. I was not even obligated to tell the FA. The passenger however was obligated to put his bag where it belonged. His violation of his obligation and outright selfishness in willfully optimizing his own space at my expense merited no consideration in even the leasest amount.
Never yield to bullies and always fight back 2X harder. It is the only thing that works.
I suppose you didn’t have to tell the FA, you could have just left it in your way. But I presume you wanted the bag removed.
I guess you also could have just put the bag in the aisle. Of course, it would be a tripping hazard, and the result would still be to get the FA involved.
I suppose you could have even picked up the bag and walked it off the plane. But I wouldn’t want to place a bet on who would win a court case for theft if the guy decided to press charges — I doubt “seat possession” would qualify as an exception that allowed you to claim access to someone else’s private property.
My point is that while you had no obligation to touch the bag or move it, since you WANTED it moved, there were probably obligations related to HOW that move took place, even if the only “obligation” was to pick up the bag and throw it into the aisle or another seat.
I would also be surprised if there was any actual case law as to where a passenger is allowed to place the bag, and I am interested in whether the airline putting a bag off the plane like that will even pass muster in the end, although an airline has a lot more law on their side than a passenger.