I think you're right. With the pressure of the crowd, being on national TV, with Trump putting the pressure on him, an earpiece with someone else talking to him, then he has to remember what they said and spit it out in a few seconds of hearing it ... that will totally confuse him ...
I don’t think there will be an audience at the debate site.
This occurred to me recently. I wondered at them having, like, 6 people in the "crowd" to hear Joe speak. It dawned on me that maybe a large crowd would be frightening to him at this point; or, just such a distraction that he couldn't function. And, maybe, this is, one of the reasons, why they are restricting the number of people that can be in the "audience".