Hmm. Well the issue is that he's using Signal, and that it's on a consumer grade phone, that is akin to deleting evidence.
But at this point disappearing message is more like limiting how bad this behavior is rather than aggravating circumstances.
I mean he's wrong to be using that setup but if using it I much prefer those illegal messages not be present anymore when he loses his phone or something.
It is illegal to destroy records of US government communications, especially at a high level, without first receiving approval from the National Archives.
But at this point disappearing message is more like limiting how bad this behavior is rather than aggravating circumstances.
I mean he's wrong to be using that setup but if using it I much prefer those illegal messages not be present anymore when he loses his phone or something.