I've had customers "threaten" me with the same. Some people get really unlucky(had a customer receive two defective products in a row and the third time we were OOS). I've never begrudged a customer for sharing their experience with others as long as its a factual account. In fact with that customer I confirmed his account of events and apologized publicly.
If your threat is to tell your side of the story I don't see a problem with it. Ivehad customers do that with me and it's usually because their experience with my company sucked.
