Are they coming to UK at the same time?

Are they doing samethings during this period? As you mention He has two years saving, so he didn't attend any school for more than one year. If that is truth, not much anybody can do. If he has part-time school record. You can appeal siad, don't know overseas students can not be part-time student.
If Homeoffice get on hold his passport. It's must be very serious issue. Check with real solicitor (there are many 'law centre' in London and around the UK, search 'law centre' on google and find the immigration one).
Good luck and all the best.