In this particular situation, Hegseth had two choices.

1. Limit what was shared in the Signal group to non-operational details and refer all involved to their secured systems.

2. Make it easier for everyone else and just post the details directly in the chat.

He chose the one that he thought would curry favor with other members of the administration.

(I assume/will try to interpret as...) Meaning that the role has some rules (written and unwritten). I can gossip about what went wrong at work today when out drinking with friends without breaking any laws/contracts, or I can just shut up and not gossip/brag that "today we killed 100 people", especially when celebrating the death of people.