“As if i had no choice but to move”: Woman refused to switch plane seats

Approximately one or two months prior to the trip, the airline contacted me to inform that they wanted to upgrade my seat to first class as a result of my accumulated points and membership status. This was my first time flying first class, and needless to say, I was beyond thrilled.Before my flight, I made certain to take care of everything possible in the lounge, and I was greeted with an incredibly comfortable setting for the 13-hour flight. Approximately one hour after takeoff, a flight attendant approached me and inquired about the possibility of switching seats with a 10-year-old boy from economy class. The purpose was to allow the boy to sit with his family in first class. According to the information I received, both parents were members and had received upgrades, but they were unaware that their son was not eligible for an upgrade. As a result, they were able to enjoy first-class tickets while their son remained in economy class. The flight attendant presented me with alternatives, implying that I had no other option but to relocate. She mentioned the possibility of receiving another complimentary upgrade on a different flight or obtaining a full refund for my current one. I inquired if it was possible for me to remain in my seat, as I believed I was being asked to vacate it. She explained that the two parents and I were the only passengers who had been upgraded on the flight, and there were no additional first-class seats available. Therefore, in order for the boy to sit with his family, it was logical for him to occupy my seat. In a different scenario, like if the first class had been overbooked and the boy had bought a ticket, things would have been different. However, I received this upgrade due to my frequent flying with the airline. I might have also considered it if the parents had purchased their tickets, but they hadn’t. I hold no ill will towards the flight attendant; she was courteous and respectful throughout the entire situation. She accepted my decision gracefully, reassured me that everything was okay, and assured me that they would resolve the issue. I never caught sight of the parents as they were seated far from my position. However, I was reprimanded by an elderly woman in the adjacent seat, who scolded me for allowing a child to sit alone for 13 hours. The thought of a child enduring a 13-hour flight unaccompanied is indeed daunting, but I observed the child walking up and down the aisles to meet his parents every hour, so he was not truly alone. So AITA, because supposedly this is what an a-hole would do?