Ask for a conference with all of his teachers and the school counselor/psychiatrist. Whomever would handle these issues. Ask the teachers outright if they understand TS. Ask the counselor to explain in his/her OWN words what might happen with a kid who has TS in a classroom. Make this person spell it out so it isn't a Mom rant. Then confirm and add your own information and personal experiences.
Teachers are often overwhelmed with information and many of them simply resent having to deal with a kid who has special needs. But make them do it. You have the right and your son has the right to a good education without being bullied by teachers who don't understand.

Unfortunately, we went through the very same thing with both our children. This is why we now homeschool, with amazing success.

Thanks for that I will do that

You need to set up an appointment with a doctor/counselor, the school, and yourself, and make them understand. It's extremely sad when a school does things like that, especially when it comes to things that he cannot help. I am truly sorry to hear that, and it should never happen. A school should, and needs to be more understanding.