But if you receive a request from a person in uniform, especially a pilot, you feel compelled to do what they say. I know that I would react far differently to a pilot asking me if I would mind sitting elsewhere compared to a regular passenger. Assuming the person in uniform was in their assigned seat, this whole situation was absolutely none of their business and they never should have intervened. Especially if they told the person in crutches to take the other seat.
In this scenario, I would rather force crutches pax to move so I could sit on my own rather than have to endure the flight sitting next to the angry employee who is presumably irritated by me for forcing him to move. But ymmv...