Makes you wonder why some PPLs do this kind of thing, when their instructors are clearly not up to the job....How to fly an aeroplane is just one thing; all the bumpf that goes with it is just as impotant.
Pilot in Command is just that. That includes checking the NOTAMs, and if necessary, checking the stude has checked the NOTAMs (properly!) etc
The buck stops with the PIC I'm afraid, and I bet he's kicking himself (or the student!)...