I earned my Eagle at 14. Some Scouts advance faster than others. For his Scoutmaster to say at this point "he needs to slow down" is to little to late. For me Scouting was (and still is) a priorty. When I was working toward Eagle that's all I did (including homework). This is also not sending a good message to the other Scouts in his troop. If your Scout has fulfilled all the requirements for the rank than he deserves to be awarded this highly coveted honor.
13 years old is young. I'm sure someone has checked to make sure the timeframes in between each rank are on the up and up. If every