I wasn't thinking years, but months but I didn't know about the recent upgrade. At any rate, if the pagers allowed any data exfiltration they have been collecting that data since whenever the last upgrade was.
So no data exfiltration was possible using the pagers. The only purpose of the modified pagers was to maim or kill their possessors, by detonating all of them simultaneously.
It's how the TV detectors work in countries, such as the UK, that charge a license fee for TVs.
Military radios can't use this common technique because of the risk of detection.
I suspect pagers only receive on 1 or at most a few frequencies. If that's correct, they wouldn't need that technique.