I do not believe he is still speaking to the choir. He is addressing the congregation - those who sit in the back and observe, as opposed to getting involved.
Just my opinion.
Besides - one aspect of persuasion that the left has long understood and the right has long neglected is the repetition of information. That is why the lefty lie has such longevity - they repeat them until they are taken to heart.
Very true. Which makes the whole political persuasion game an interesting combination of the subtle (tactics) and the crude (repetition).
I noticed a couple of years ago a characteristic of Rush Limbaugh that had previously escaped my notice. And that is the high degree of repetition as he expounds on a particular topic.
Radio broadcasting is typically a one-way conversation. In a two-way conversation, one can pick up subtle cues that the other person is following an argument. If necessary, one can explicitly seek confirmation of understanding with a question.
In a one-way conversation, one must make sure that the listener understands the question before one provides the answer; otherwise, the answer will be out of context and a waste of time.
Like Rush, Trump speaks to an audience using similar tactics. He will repeat the key point several times using slightly different phrasing. If, for example, he is illustrating how corrupt Hillary is, you will first hear him mention a couple of times the phrase, "crooked Hillary". He understands it will be a waste of time to describe her crookedness if some portion of the audience loses track of just who he is talking about.
Rush augments his speaking by having listeners phone in. This too helps him drive home his points by providing even more context for what he is saying.
My eight-grade teacher emphasized that "studying is the repetition with the intent to learn". Without the repetition the audience might hear something but they won't necessarily learn anything.