Exactly the problem
If those disillusioned kids were allowed a voice for their own future without heavy handed ham fisted directions being sent down from their CCP overlords none of the violence would have happened.
The Chinese government puts Face above all else, it's like having a proud and arrogant father who will lie on his death bed with no friends or family around rather than admit he's wrong.
Banning HK youth from any events for having an opinion will make things 10x worse for all involved.