He is extremely lucky that other westerner intervened.
It just shows the arrogance of this guy - 200 baht!!! Just pay it and move on. Look I know not all Americans are like this, they are usually very generous people, but this guy is giving Americans a very bad name. Jesus Christ!!! Welching on a debt of 200 frigging baht! And then criminally assaulting a staff member.
I hope he rots in jail. It will give him a new perspective on life.
And he should thank the westerner you stepped in to protect his stupid arse.