I don't think Air Force Chief of Staff is an office that is privileged to the levels of sensitive intelligence that you're proposing.
The Chief of the Air Force is the TOP DOG, who else would be privileged or even interested??? he is also a fighter pilot, and understands not only the hardware/avionics but the mission sets. Air Force officers at many levels have "top secret" clearances, my old man ran the USAF Air Ops out of the US embassy in Saigon, as well as initial testing of the AC-130E in combat ops.
To make a statement that the Air Force Chief of Staff lacks the security clearance for any and all the information on the J-20 is just flat denial of any truth. He prolly knows the number of rivets on that bird, if there is any information of that nature, he is fully briefed, and then "schooled" if necessary. I will guarantee that he understands both the J-20 and the T-50 design, mechanically, and operationally, to deny that is simply to be in denial.