Does a lid on a pot safely "seal" soup?
The seal, the pot, none of it really matters.  

You don't sterilize food when you cook it, you pasteurize.  

Even if it was perfectly sealed, there's still baddies that didn't get killed.  Pasteurization brings food bateria to a safe level, not a 0 level.  Once food gets back in the 'danger zone', it can start growing pretty quick again.

This is the same reason you can't cook a sous vide meal and then leave it on the counter forever.