when a school over punishes a child is it considered bullying.

On October 15 my son rode the bus to school. There was another child that was carrying a shirt that had wet paint on it. The kid wipped the paint on my sons hand and my son wipped the paint on the seat. They suspended him for the rest of the school year because of this. I went and watched to video from the bus and I told them that being suspended for the rest if the school year was not the right punishment. I requested that they lower it to 15 days. And that he clean the paint off the seat. Rosetta would not have it. So I went to the superintendent and Rosetta lied and said that she was trying to work with me on a sutable punishment. Which she had not contacted me. At this meeting they said they would reduce it to 30 days but he had to clean the paint and sweep the entire bus. I did not agree because that is over punishing a child. So I went to th school board and they are sticking to the 30 days plus clean the paint and the bus. This is not a fair punishment.