He could go through with the audition if he likes the school for the general quality of the music department. If accepted, he can then have a lesson before making a final decision. The cello prof will likely be more available and accommodating to an accepted student. If the money isn’t enough, it can be negotiated after acceptances, especially if a peer school has offered him more and/or the cello prof really wants him.
How does he feel about the overall quality of the entire music department? Has he evaluated the orchestra and chamber music program for appropriate opportunities for growth? What is the quality of peers in the cello department and other strings? Good student colleagues to grow with? An individual teacher such as the cello prof can always leave, retire or die during your son’s tenure. It happened to me as an undergrad and one of my kids at major conservatories. You want to make sure he likes other aspects of the school in case the worst happens.
I would also consider it a fair question to ask of the admissions department about the situation with scholarship awards if the cello prof will not be listening to your S’s audition. I wouldn’t hesitate to ask the question as a parent, but others on this board may feel your son should make all the contacts with admissions. Personally, as I said, I would call anonymously! No one will be keeping track of calls like this, but you may get a work study student who can’t really help you out.
In my experience, this situation where a panel not including the preferred teacher hears an audition.occurs at other schools also Often auditioners are ranked in some manner which indicates the possible level of award the student is “eligible” for vis a vis other auditioners.