I also agree that the airline personnel should make the arrangements concerning seat-switching for a disabled passenger. It isn't fair to expect them to have to explain personal details to a complete (angry) stranger standing in the aisle.

On one flight we had to book at the last minute a few years ago, I hadn't discovered FT and had no idea there were so many seat-poachers in the airline world. On a flight with only coach seats left for sale, I was in the aisle seat, and the poor businessman next to me in the middle got "that look" in his eye when I started a conversation. He was in front of a small child, and when he realized I was not only not a VBIT but was offering him the aisle for his middle, he must have thought I was crazy. But I could recline in good conscience in front of a small child's seat, and I have a bad back.

He got the aisle, I reclined after playing "peek-a-boo" for a while until the child fell asleep after take-off (really, a very well-behaved and sweet child) and a pleasant flight was had by all.