I know nothing of such a show - "Pointless Celebrities" but it doesn't sound like anything I'd want to watch.
If it was/is as grim as it sounds, why on earth would any caring soul allow someone who might need "looking after" onto such a thing?
Oh well. I know little to nothing about his life after I stopped watching Blue Peter, which must have been in the early 70s. He was a major reason why I watched Blue Peter - the others were very "BBC" of the time, but John was something of a maverick, jumping out of planes, riding bobsleighs and the like.
Thanks for all that, John. Bye.