The fact is the mother repected his request, although the baby just like all of us, is a human being, and although not charged for the ticket, deserves comfort just as the aisle guy does who decided to check into an aisle seat with an empty middle seat. Just because the child didn't have a paid ticket, airlines go out of their way if there is an open seat, to assign the single mother traveller with child for that extra seat.

Sit the child down first.. bleed a bit.. fine over the armrest.. or lift the armrest and be a bit more comfortable.. The main thing is there is lots of leg room under.. so that's his real estate.. but c'mon, denying another human being a seat when one is available because you can't move your fat a__ is treating another human being unequally IMO and hurting a child by denying comfort for his own selfish reasoning. The guy in the aisle use to be a kid as well.. very unlikely a stranger would treat him like that when the aisle guy was less than two years old.