Yes, it is safe. They are saying that the acidity did reduce the E.coli over long exposure (6 hours), but the effectiveness was decreased by the addition of dilute amounts of other acids.
What is more important though is that vinegar sitting on a store shelf is going to expose any bacteria to the acid for longer than 6 hours. So it is unlikely that any bacteria would survive in the acid after a day or two at the most.
Secondly, stomach acid is a much stronger acid than vinegar. This again is a major reason we need to maintain our stomach acid. One role of stomach acid is to kill ingested pathogens.