muppet - By that logic, anyone sponsored through university would not be on the UAS, so I think you're off the mark.
OP - downsizer has a good point regarding a bursary. Your son can still go to OASC as a student without being on the UAS, and might win a bursary for the final 2-3 years of his degree. This would automatically get him onto the UAS where he could take advantage of the flying (with an emphasis on the out-of-term 'camps' due to the intensity of his studies). Could be awkward for the person who told him 'no' if he got in!