“What do you think, what is causing Joe’s “blunders”?”
It’s certainly a low IQ thing and add to that dementia. If you had a low IQ to start with, dementia and old age will NOT improve the situation.
Biden is long gone. Bidan (sic) is a good guy. Bidan is a great actor. He was scripted to 'what am i doing here' in a senile like way.
So, rather than an "IQ thing", I'd say it was just a Q thing.
YMMV.