At least in the UK, you can fly passenger transport aircraft with a prosthetic lower arm, two if you have a suitably rigorous inspection regime for the prosthesis.
By way of example, here's the story where a FlyBe pilot's arm came off (but did not seriously endanger flight safety):
https://www.bbc.co.uk/news/magazine-28785171
If the FAA allows similarly, then a "DIsabled" person could apply for this job. There may be an above average proportion of people who tick all of "Disabled", "Veteran", "lots of flying experience", and "TS clearance".