Is it true that if you hold government security clearance you're already in rap back?
If you really want to know, do some research into the FBI Next Generation Identification (NGI) System.
"Am I in RAPBACK" is a two-part answer.
Part I: If you are providing fingerprints, photos, retina scans, DNA and other biometric identity information, you are added to the NGI database.
Part II: HPD wants to SUBSCRIBE themselves to the NGI reporting system, which is RAPBACK. If you ever encounter law enforcement in any state, the Hawaii Criminal Justice Data Center receives a report on your activity. They then send the information to HPD or anyone else who subscribed to receive your reports in RAPBACK.
So, even if the subscription is canceled in accordance with the posted policy, your information will forever be in the FBI database.
If having a clearance adds you to the NGI database, you are already there regardless of whether the agency adding you subscribed to RAPBACK. Only HPD can subscribe you so that they receive updates for the purpose of assessing your fitness to possess firearms.