As someone with dyspraxia, he has my sympathy. This kind of verbal mix up, is not uncommon with dyspraxia. I am renown in my family for mixing my words. That may well be his problem because I think these slip-ups. and misuse of words has been a feature in his life from quite early in his career.
Biden was the preferred Democratic candidate for President from, to be honest, a pretty mediocre bunch, but he was chosen and elected and since everyone saw his slip ups, of both kinds before the election, but still thought they would rather have him than Trump again, I cannot see what all the fuss is about.
He has also chosen a very competent Vice-President who is mroe than capable of taking over if anything happens to him. I think that was a deliberate choice.
Lets stop worrying about his age and trips, there is nothing anyone can do about them and concentrate on his decisions. When his decisions get irrational is the time to worry