How is this preferable to using government issued devices with government controlled communication software?
From what I understand, it’s certainty not preferable from a security perspective.
I really don’t have a good handle on this, but I believe “secure terminal equipment” are basically desktop phones.
So if you are using Signal, you are choosing convenience (everyone can participate regardless of where they are) and sacrificing some amount of security. The references to “high side” in the transcript shows they are cognizant that some items couldn’t be shared via Signal.
Many/most security experts believe some of what was shared as far as strike times shouldn’t have been shared on Signal. They should own that and implement changes to eliminate it from happening in the future.