Frankice
If he failed to go around because he was unable to go around or because the FO was not briefed to take control or allowed to take control then there are issues which need to be addressed so that there cannot be a recurrence of the event.
If he landed on a wing and a prayer then he was lucky the landing completed without damage.
either way it does not appear that missing an arm at such a crucial state of the flight allowed him to be fully in control. He was lucky this time and i am sure measures have already been taken to make sure that any unlikely future occurrence will be handled in a different way.
Of course he should not be stopped from flying! All indications are that he is a competent and good pilot but procedures unique to him will have to be put in place for the future.
My Seneca pilot an able bodied pilot was literally mentally disabled by being a passenger to the well known wheel breaking Seneca porpoise. His was a sharp lesson and i am sure he will never make that mistake again and the same goes with this physically disabled pilot