No, it’s quite simple.
The TOPIC of the chat is the key, second factor is, is the conversation one that BY LAW has to be recorded and kept.
Talking to your boss about a grievance - in confidence - Signal is ok.
Talking to a concierge about a business trip is also ok.
Comparing notes before an official government meeting - also ok.
Using it to discuss a military operation - not ok.
Because, as this leak shows us, there's no protection against an unverified, non-vetted number being added. Do I have it?
I wonder who owns Signal. Will this cause their app to be downgraded? According to another story someone just posted, several administrations in DC have been using it since at least 2017. (Although perhaps not for conversations like this.)