That one of the people with criminal charges is an employee of the library who tried to get the guard to stop assaulting a member of the public:
> Both the librarian and the patron face criminal charges.
That the guard had ignored their instructions about not interfering with people who pose no risk of harm to the other guests:
> According to the library, as part of the agreement nobody was to be prevented from asking a controversial question and the security team would consult with library officials before ejecting any nonviolent patrons.
That the question asker had offered to leave if asked?
> Rothe-Kushel can be heard saying, “Ask me to leave [and] I will leave.”
and so on.
I mean, this ...
> When he bounced out of the chair onto the floor, the guards forced him back into the chair, and handcuffed him.
... is a criminal offence in England.