I could agree with that. I think it could be taken either way though. So what if the person stays in the vehicle then? Doesn't get out, just waits to transport the person from the school function.
If this were to happen, and the person arrested got a good attorney who filed various motions, judges would look at past cases. In this kind of case, DUIs are a great example. There are specific instances where a person has been ruled to be "operating" a vehicle even though the vehicle is in park or they are passed out. There is certain language used by the courts in these cases. I think a good defense attorney could make a good argument that as long as you were in the vehicle, in the driver's seat _and_ that you did transport someone to the grounds, _and_ you were transporting someone off the grounds after x amount of time, then you _might_ get off. Of course you better be ready to pay thousands in legal fees for this.