...the entire episode was about the captain torpedoing her own boat after Boimler told her that, though?
ETA: Not to mention, that was still not supposed to be reported to her. The point is he was not supposed to say thing X to person Y. That goes for whether he's talking to the captain in the lift or doing peace negotiations with Romulans. Boimler shows that he cannot do it. He may in the future, but he cannot now.