Note for all about the Signal messaging app. While the level of stupid for someone to have a secret level government...

[drray23]

2. Completely agree. Especially your last part.

About the device itself. Even if encrypted in transit and assuming major state actors can't break it, it still leaves the device itself vulnerable.
Personal phones can be compromised. Each time I have gone on an official trip ( on behalf of DOE) in a country considered a security risk ( like China, Ecuador) I have to use secure laptops and phones and I am not allowed to take my personal devices.

The laptop has minimal functionality, can not accept USB keys and it's network acces automatically disabled upon landing back in the US. Once returned to IT , everything is wiped out. Same for the phone. It's blanked out anew.

For the physical breaching of the phone, we were told to never let it away from our possession and be wary of random people trying to befriend you, especially young attractive people.