I honestly do think Biden has cognitive issues, but also people trip. Even geniuses trip! Embarrassing, for sure but I've tripped in front of people before!
And perhaps on his first stumble he hurt himself, being an old man, and didn't instantly recover. Weird!
What I mean to say is, if you have a problem with him and think he's not "all there", that's fine. But "haha old man slipped" is kinda silly