Angry father boards school bus and threatens kids bullying his daughter who has cerebral palsy

I know that threatening anyone, let alone kids on a bus, is morally wrong. But at the same time my heart is with this father who would give his life, his reputation, his everything to protect his daughter. Modern society is not yet equipped, legally, in terms of dealing with the profound psychological effect childhood bullying has on children. It's hard to codify an appropriate law to prevent bullying without infringing on peoples' freedoms (false accusations would be made, for example).