At that time, Charles was using Mark Bolland to smear both his brothers in the media. The Daily Telegraph reported that any suggestion put forth as to what Andrew's role should be was challenged by Charles.

Charles already pushing for his slimmed down monarchy which was consist of his parents, himself and any future spouse, and his sons (who were only 18 and 16 years old) and their future spouses.

He clearly had an agenda, so it's not surprising that his parents didn't listen to him. No matter what "job" they suggested for Andrew, he was not going to approve.