I got into an argument with the person behind me on my last TATL. Apparently when I reclined it ruined his angle to see the PTV in the seatback (I thought these things could adjust, but this guy was pretty tall). I agreed not to recline until after he finished his movie. Next day after the flight I had severe back pain from sleeping upright for several hours. I agree with OP, don't let anyone bully you into putting your seat up.