I don't think you need a LLM for that. Back before 'AI' was all the rage, there was a website in French that could generate a double speak/political cant with pretty good accuracy.
It obviously has much more vocabulary, and bigger words than Trump, but I think it could easily be dumbed down to his level.
Then again, it's probably easier to just collect his non sequitur diarrhea and have a script randomly quoting bits of them.
Like, there is no need to waste energy and time on random gibberish. He's already doing all the "work". Just collect these and show them randomly for a braindead experience.