I remember talking to a friend of mine after he announced. We're both native New Yorkers who have watched Trump for far too long. Both of us are politically aware/active.
I told her that Trump was in the race and she told me that she didn't want to have to think about Trump.
Also, most of the crowd that greeted him that day were paid actors.
I actually think this is what they're doing. Trump would by far benefit the most from a hot mic - talking (shouting) over his opponents is like half of his debate "strategy" and it sadly usually works out for him. Even with courtroom experience I'm not sure Harris can wrangle him.
However, taunting him into accepting a more formal debate structure with muted mics and speaking in turns would take away his favourite move.