Yes the USPSA has a junior program. They do have a website for the junior program also. I would look here for your answers, but to my knowledge yes he will be able to shoot.
MY SON STARTED WHEN HE WAS 10. HE HAD HUNTED BEFORE. HE STARTED WITH A HI-STANDARD 22. HE MOVED UP THROUGH A 380 TO A S&W MOD. 3914-9MM. HE SHOT THIS FOR A YEAR (TOTAL TIME A YEAR AN A HALF). AT 12 HE NOW SHOOTS A PARA-45. HE IS MM IN IDPA, AND "D" IN IPSC.
THE 45 TOOK A WHILE TO "MASTER", HIS SCORES PLUMMETED FOR AWHILE.
BOTH IDPA, AND IPSC WILL LET THEM SHOOT, AND BE MEMBERS, PROVIDED THE PARENT AUTHORIZES IT,AND STAYS WITH THEM DURING THE FIRST FEW MATCHES. (RIGHT BEHIND THEM)