His speech writers are getting off track as liberals so often do. They should have him stick to the core message and let others complain about the side issues.
Or maybe the they realize the core message is already getting old and need to broaden his topics to extend his 15 minutes and continue their free campaign time on CNN.
Maybe they are short on actors and are forced to use him. Maybe he was one of the few, or the only, “planted” student. Or maybe others are too easily recognizable from other crisis events.
Just spitballing some guesses here.