Defer it

First, ask your son to handle it, it is his duty, not yours. If you found wrong information for him, it's him who is going to jail (in this case, no jail, of course, but I am making a point), not you.

Second, HE should talk to the court clerk to find out whether college students are exempted. CA does not, but MI does.

Third, if he was not exempted from jury duty, HE could defer it until he is in town, typically during summer or holidays. Schedule around holidays is a good if you don't want to serve since there would be almost no trials during those days.