This is some hilarious gamesmanship on Trump’s part. Trying to live rent-free in Biden’s head.
At the start, DJT should casually, off the cuff, suggest he and Biden pledge allegiance to the flag. There will be one on stage, and why not?
That alone will throw Biden off his game for the entire debate.
Even if (Big IF) Biden successfully recites the pledge this time, he will think - throughout the entire debate - that the whole world knows how he just screwed up the pledge last week (for real) and that alone will mess with his mind and preoccupy his whole thought process for the entire debate.