Seems like a stretch. If you really want to find the CIA's janitor just drive a passive cellular monitor near it and grab everyone's IMEI and cross-check it. Plus if someone has a full time job with security clearance working for the USG they likely aren't getting a free phone anyway.
I'm not a spy or imaginative enough to lay out a scenario, but remember if someone has a security clearance, then someone, who is assumed to be the Chinese government, likely has their entire file (clearance investigation, fingerprints, you name it) due to the Office of Personnel Management having everything stolen. So this could be used in synergy with any other tactics applied to CIA agents who aren't compromised by the OPM or people without clearances.
