You asked us if the Zetec was an interference motor or not. We have told you that, in fact, it is not.
That was your question and it's been answered. The Zetec is of a non-interfering design!
Keep in mind that it's the tales of destruction that need to be closely examined/verified as to why damage occured, not whether the engine is of a different design than what Ford says it is.
Too many factors could come into play that could cause bent valves accompanied by a snapped belt. You never know if a person has neglected maintenance on a car, abused it, modified it (milled head, different cams, etc.)... it's always possible that some engines experience catastrophic valvetrain or other internal engine failures which lead to bent valves, and a snapped belt, damage which could easily be blamed on the belt.
Also realize that when you ask a shop for information, their first interest is getting into your wallet, so it's not surprising that they'll make it sound risky to not get that belt changed right away. It would also make sense for an aftermarket company, especially a cam gear manufacturer, to use a disclaimer like that so they're covered in case someone doesn't change their belt and the engine blows up.
