My understanding is that this doesn't actually say anything about whether or not life exists on Enceladus. It's just that the presence of phosphorous is something life as we know it on Earth requires, so seeing it on Enceladus checks another box like the presence of water does. It doesn't necessarily imply the existence of life on its own.

The whole life on Venus fiasco was a bit different. Astronomers thought they had detected phosphine on Venus, which is a chemical that we don't believe could exist naturally under those conditions unless it was catalyzed by the metabolism of potential microbes. Unfortunately it turned out these astronomers hadn't actually detected phosphine.