The signal chat did not have anything that someone would try to hide. People want easy things, they want to manage an air strike using their mobile phone from their bedroom. They don't want to sit in their office for that or use some hardened government issued device that is older, uglier and an extra brick to take along, with no real support of IM (my assumptions on DoD devices)
some years ago it was unthinkable to manage a battle remotely, now it is common practice. This job changes too.
In any case the same issues you have in a regular company also exists in the upper echelons, no reason you can't give them technology that is encrypted and easy to use. That doesn't mean they are supposed to use Signal though
The signal chat did not have anything that someone would try to hide. People want easy things, they want to manage an air strike using their mobile phone from their bedroom. They don't want to sit in their office for that or use some hardened government issued device that is older, uglier and an extra brick to take along, with no real support of IM (my assumptions on DoD devices)