Why don't you contact the school and see if he ever attended as a student? Being discreet, of course. I'm not sure if the state data protection law will allow for that, but most educational establishments take a dim view of people trying to piggyback their reputation if they never actually attended! Alternatively, if you're not afraid of losing the tuition of this teacher, why not just outright ask him? The information this thread alone should be enough to equip you with the knowledge that surely any Berklee grad would be at least able to read treble clef.
Where the grey area may be, is that he does not feel confident in teaching treble clef and may be out of practice with reading it. But if that were the case, wouldn't you just say so?
Where the grey area may be, is that he does not feel confident in teaching treble clef and may be out of practice with reading it. But if that were the case, wouldn't you just say so?