Shutting it down would have made every single existing radio controlled clock e-waste, overnight. And not just random wristwatches and wall clocks, but school and industrial clocks. None of these will work with GNSS signals.
That's the point, to stop creating this e-waste. If those applications are critical, then the owners should never have bought vulnerable radio controlled clocks in the first place.
Your assertion doesn’t even make sense. The hardware (wall clocks) could be older than gps. And gps is not only more expensive to receive, it’s harder too (most of those clocks would be indoors).
Radio clocks are vulnerable to signal loss and spoofing regardless if it is GPS, cellular, or HF. If the time accuracy is critical, then the time signal should be delivered by wire to device, especially indoors. Wall clocks should have a manual way to set the clocks given there has never been a guarantee to receive the WWV signal. If expense is the concern along with wireless capability, then an integrated 2.4GHz SoC could be used that costs pennies; https://www.beaglesoft.com/radsynreceiver.htm appears to cost hundreds.
