No it isn't. If that's the case then he could have the school pay to get his car pulled out of the snow. I don't see that happening. If he was riding the school bus to school, then they might have a case.
School time and school rules do cover the time to and from school. The school no more has to pay for his broke car than they have to pay for his broke calculator, if he drops it on the floor in math class.
However, he is subject to school rules during that math class. (And during the time to and from school.)