He’s building anticipation and suspense (and a larger viewing audience).
He's a smart politician, then!
Actually, a lot of people are at work or need to get there. What appears to be a broad-themed speech may not be sufficient to allay the concerns of many who want to know how in the world he got caught up in this hate cult.
It's also interesting that the man who had reservations about wearing a flag pin on his lapel, now has eight beautiful flags on stage.