He knew exactly what to share and what not to share based on whom he was delivering the news to. This is also essential to progress towards a successful endeavour.
Notice the quality of leader, Rama in this scenario. He asked the right question to find out who actually met Sitha for testing validity of the news. As Hanuman answered, it was clear to Rama that he was the one who reached Sitha. The rest were all only reporting what they heard from him.