How about this as a scenario: Such safety mechanisms are engineered at first. A rare earth element is used as the cofactor. After a number of years, an organic cofactor is introduced and becomes widely adopted by industry as it reduces costs. Since this works so well, industry becomes cavalier about the release of such organisms, as they all soon die anyways.

A rogue bioengineer creates an artificial organism that can produce the cofactor. Hilarity ensues.