Some years ago I was a passenger on a flight from Florence to LHR. An elderly male passenger with two walking sticks was seated in the seats beside the wing emergency doors.
I politely pointed it out to the cabin attendant who said it was in order. I asked her to inform the captain. (All politely and in accordance with How To Win Friends and Influence People - I was at that time teaching Pax handling to BAA). She returned and said the captain said it was OK).
Aware of the very sensible flight safety regulations I told her that I would of course have to accept it. (I didn't fancy a night in a Florence pokey).
However - somewhere over France the old gentleman was re-seated at the front of the aircraft which turned out to be very convenient for the electric cart he needed when we he disembarked at Terminal 5. I noticed that he couldn't lift his case off the carousel let alone the 20kg disposable hatch he had been seated beside. Though I would add that happily that had not been necessary.
Upon submitting a report, I was a bit reassured by the CAA controller's assurance that the captain had in fact NOT been informed by the cabin attendant, and her report to me of his comment was false.
Perhaps that should be made a subject of air safety regs?