Restraint is one thing. Not being familiar with how to use force and when it is appropriate is another. Once this guy hit an officer, force is justified and required to stop the threat and maintain peace.
It looks more like the police here are used to just talking with people rather than the uglier side of the policing profession that requires that they are comfortable with conflict and use of force - sadly it is part of the job.
Not to totally sideline quarterback, but this situation likely could have been 100% avoided if this guy was cuffed properly in the first place ( upon first contact and to the rear).
Mind you, part of the charm of Taiwan is that it doesn’t have this level of violence to deal with normally, and thus why the police are like that …