^^Paying the $1500 in fees definitely helped your son. If it would have been used for another purpose than fees, he would have been taxed on the $1500 and had to pay the fees OOP. You would have gotten an AOTC for a percentage of the $1500.
You could have ‘shifted’ the $1500 to taxable payments (travel, room and board), had him pay the taxes on it, and claimed the AOTC.