Appreciate everyone's opinions. Like I said before, I am totally OK switching seats with someone in need. But the way it was handled was a bit strange, if not off-putting. If the pilot decided to switch my seat without asking the flight attendant, the right thing to do - when I requested an aisle seat - is to offer his own aisle seat (3D) and go to the disabled passenger's seat (3F) that he decided to swap with my seat (3A). All of a sudden he wants me to talk to the flight attendant because he doesn't want to give up his seat. Thankfully, the flight attendant did the right thing and asked the pilot to move to 3F and gave me 3D.

After boarding was complete, I swapped my seat (3D) with my spouse who was in 2A. I did not want to sit next to the pilot who rolled his eyes at me for asking an aisle seat.