There’s one kind of intelligence that comes from an accumulation of knowledge within one or more specialized areas, and another that relates to being able to objectively and accurately analyze information not closely related to any of your specialized, accumulated knowledge.
Many revered as geniuses based on the former are often found lacking based on the latter, and it seems that is the case here. Just think of how many “smart”, elderly people you know that couldn’t adapt to any new technologies as they came out.
It took my Dad a long time to figure out how to operate a VCR, and after watching his first movie on a rented disc, as he was getting ready to return it he asked me “Do I need to rewind this first”?
With Hawking I had been chalking up the foolish things he says off subject to just a smart man addicted to attention. But this latest example makes me fear there has to have beeen some mental deterioration as well. Its not even plausible on an “ancient aliens” or “coast to coast am” scale.