It's a big difference.

Signal is secure. (Even the 3 letters are using it.)

But like with all the other security tech, it's useless when you don't check the surroundings.

Like a save, with the keys next to it. Or a bulletproof car, but you drive into a lake.

Or, better match for this case: While letting the water run, you whisper a personal secret into the ear of THE gossip girl of the town.