Yes, it cannot be created naturally.
The concern is that if one of the mirror proteins is able to be cloned naturally, then we would have a problem on our hands.
However, those mirror cells would need a supply of “mirror food” such as “mirror sugar” in order to survive their natural lifespan. And then they would need to break apart into the mirror proteins that can be cloned. Racemic drugs like Thalidomide do not behave the way they are talking about in the article.
I have my doubts that this is an actual concern. It’s not even similar to prions - prions are misfolded proteins that have the same chemical make up, but the natural enzymes end up cloning those over the natural ones because they are easier to make.
See I didn’t know that, cool thanks