The Secretary for Security suggested some protesters had received support from foreign organisation at the Legislative Council on Wednesday.
Chief Executive insists she has full confidence in Independent Police Complaints Council (IPCC).
Leung Ka-kei, 24, was stopped at an immigration checkpoint around 11.30pm on Sunday as he was only allowed to travel starting midnight on Monday.
It is believed to be the first such punishment for offensive language in classroom against the anti-government movement.
PolyU is yet to announce its repair costs, while CityU earlier said its restoration costs would reach a nine-digit figure.
The march initially had permission to proceed, though police attempted to end it just hours after it began.
The city’s ongoing turmoil is affecting kids' behaviour and early development, and it's important not to ignore its effects.
Police fired tear gas, pepper spray and rubber bullets, and deployed a water cannon in Kowloon as protesters occupied roads.
The government official said that school heads could be disqualified if deemed unsuitable while handling 'protest-related complaints' against teachers.
The Civil Human Rights Front initially obtained a letter of no objection by the police on Sunday for the rally, but the police terminated the event early.