Just for info this is more than likely something like what he uses. This one is for motorbikes.
The way I read it the bit that failed was the clamp onto the Yoke. The friction clamp lever sprung open. This one because it is semi perm can be bolted to the steering bar.
From an engineering point of view the design in use more than likely had several thousand landings on it with no issues. The event occurred design revisited and in under 10 mins the risk negated with use of a tapered retaining pin through a lug hole.
I think there are 2 engineers in the UK who can sign off mods for disabled pilots but both of them are light aircraft. There was a third but he died a few years back.