I am betting he does not show up at all. Remember, this is the guy whose handlers won’t let him alone with the press for 90 seconds. How can he do 90 minutes? Impossible.
How can he do 90 minutes?
Suppose there are 14 questions. The moderators will probably bloviate for two minutes, so
2 minute question + 2 minute answer + 1 minute rebuttal + 1 Minute response = 6 minutes
Every question will tax Biden either 4 minutes or 1 minute.
7 x 4 = 28
7 x 1 = 7
28 + 7 = 35
Biden has to perform for 35 minutes.