Originally Posted by RobinHoodNYC

I don't think anyone would intentionally choose a middle seat when there are aisle and window seats available. They may not want to be responsible for opening the door in case of an emergency. The window seat could've been taken when they were looking for seats and they preferred an exit row and the middle seat was the only exit seat available at the time they were seat selecting.

The widow seat could now be available because the person was upgraded to first.