sounds like the child needs to have the seat close to the driver.
Once seated the driver takes the stick until time to get out.
That would be the most logical solution. If repeated then paddle him. Before anyone flames let me explain. I was in a special education school for kids with disabilities my seventh and eighth grade. We had a shop teacher all of us respected and loved dearly. He was also a father of a special needs son. If a situation called for using the paddle he'd give a kid a whack on the sitter "IF" the disability allowed for it. None of us thought it odd, wrong, or mean of him. Generally best I recall no one came back for seconds and I got a taste of it once. It hurt yea but getting popped by him hurt worse than the board itself.
My mom drove a special Education bus starting two years after I left. She would have simply put him up front and took the cane until she dropped him off at home. Special needs kids with disabilities fight also LOL. But it's usually an equal match up. IOW some classmates you didn't hit period as it could do very serious harm. We didn't go there and we knew not too.
Certainly sounds like a good approach to me.