>In a natural environment this will not hold. Organisms are unstable; they change all the time, simpler ones even more so.

Jurassic narratives notwithstanding, unsure if this is a real problem. If you have a yeast that will only survive under narrow unnatural circumstances, I would expect freeing it into the wild with natural circumstances means it dies - not uses nature to find a way to destroy the world as a form of poetic justice for ever having been created.

People who have never worked with anything biology related love to spout off about Jurassic Park. As a brewer I can assure you all that fancy special purpose yeasts just don’t turn into other stuff readily and often lose their modifications when they interact with wild yeasts.