Everyone. Everyone should use a script and a teleprompter for important speeches. Obama would have used one. Trump should use one a lot more. A LOT MORE. When he doesn’t he’s a rambling mess. That isn’t really the worrying part.
I don’t think the flub is necessarily proof of either. You start reading out loud and tell me you don’t flub up a line. I will face time with the kiddo and read her Mindtrap questions, which are logic puzzles, basically. I’ll stumble on reading. I have a habit of reading too fast, not focusing on each word. So mixing up or stumbling over a word when reading doesn’t really give one a good sense of ones abilities. Does my kid read at a higher level than him? Probably. But they keep the scripts simple enough. That there would be what you would want to analyze. For the written down scripts, analyze what reading level they are at. I am betting like 9th grade or so. Maybe less, he uses pretty simple language, but also factor in that the writers may be also making it more appealing to their base who don’t like big fancy words.
Note - I’d personally challenge him to a game of Trivial Pursuit to the death.
Then again, I am not a practiced orator. He should have practiced this before - and if not, that’s on him. What is more telling his his flubs without reading. His word salad when just talking off the cuff. That is the more worrying thing where his cognitive abilities are called into question. I suppose that too could extend to mixing up words when reading, but as per above, that alone doesn’t mean anything conclusive. I’ve seen professionals on places like the David Pakman show say they worry about him having early on set stages of cognitive issues.