There will be a communique from USAC later discussing the relegations, DQs and fines. We could have a betting pool and see who gets the reason for the DQ right.
It seems hard to get DQed at nationals in the junior field unless it was something fragrant that was discussed at the start that affected safety and stated by officials that no mercy will be shown for offenders. I could see centerline rule violation being the most likely. Maybe no pins in his number. That would be hysterical.