Actually he used his left arm to gesture frequently. I thought he possibly lost his right arm movement, but one break showed him using it, although with some limit. It took real courage to him to come back. Was it stellar Clark. No, but I non the less am glad he made the show.
My sense was that this was one more celebrity who didn't know when enough was enough. Chalk it up with John Wayne's appearance at the 1979 Academy Awards - what Clark should have done was take a page from Johnny Carson's post Tonight Show years and just disappear from the tube. Oh well.