Another thing to consider is that after the balls were reinflated back to spec at halftime.....presumably in the same locker room, they reportedly remained in spec at games end.
Quite true - but the game balls had just spent two hours in the cooler temperatures, and the halftime break is brief. So the footballs themselves and the air they contained was at or near game time conditions. The introduction of a little air prior to return to the field of play would have little effect on the “conditioned” footballs. Thus, little or no change in their condition throughout and after the second half of play.