It seems like her main complaint is not that she's being expected to travel with adults or lie in the bassinet - but that the airport didn't know to provide her with a wheelchair.

I would not expect that to be tied to age! I thought anyone could tick the "I need assistance" box and get wheelchairs, golf carts, etc. Sure, they could guess that their 90+-year old passengers are likely to need them, but there are plenty of 80-year olds that need them and plenty who don't.