This phrase assumes a situation is fine when there's no update, which could relieve anxiety. Since the weather hasn't worsened, no news is good news for the sailors at sea.
Pro Tip 2/3
Uncertainty Management
It helps people stay hopeful during times of uncertainty when there's no new information. We haven't heard from the rescue team yet, but we're holding on to 'no news is good news.'
Pro Tip 3/3
Calm Reassurance
The phrase suggests staying calm and not worrying when there's no news about an event. The test results haven't come in yet, but let's say no news is good news and relax.