It's about mitigating risk and finding the right balance. I would suggest that after this incident the 1 in number has got significantly smaller so having a pilot with a prosthetic is even safer now than 2 years ago. Would we be finding the right balance if we said the safest course of action with regards to flying is to not get airborne? Of course not. Is finding the right balance letting every man and his dog with or without licence or with any medical condition fly? Of course not.
I am quite happy for the experts in their field to make up the rules and assess each and every case on its own merits. Companies then have to assess an individual's ability to complete the task in hand. I am happy to fly with the chap in question, not because he is a good bloke but because it sounds like he has a proven track record of being a good operator.......something I strive to be every time I go to work.
There has clearly been a mechanical failure between the prosthetic and the control column, but the problem was rectified and no one knew about it until 2 years later. The pilot has learnt and the industry had learnt. I would suggest that the likelihood of a recurrence is very unlikely.