The term "exotic" in a chemistry context means one of two things.
First, it can mean observed chemistry that is seen neither in nature nor the lab under ordinary conditions. In other words, it is theoretically possible but the required conditions are so atypical that the expected probability of it occurring unintentionally are very small. I'm guessing this is the case that applies here.
Second, "exotic" can mean engineered chemistry that is far outside the standard industrial spectrum, typically because there is a unique application with very special requirements. Industrial chemistry is all about price performance of the chemistry not absolute performance, but some use cases are more performance sensitive than price sensitive so people will design bespoke and unusual ("exotic") chemistry for the purpose. It is a curve. Everyone uses the cheapest chemistry that still does the job adequately.
First, it can mean observed chemistry that is seen neither in nature nor the lab under ordinary conditions. In other words, it is theoretically possible but the required conditions are so atypical that the expected probability of it occurring unintentionally are very small. I'm guessing this is the case that applies here.
Second, "exotic" can mean engineered chemistry that is far outside the standard industrial spectrum, typically because there is a unique application with very special requirements. Industrial chemistry is all about price performance of the chemistry not absolute performance, but some use cases are more performance sensitive than price sensitive so people will design bespoke and unusual ("exotic") chemistry for the purpose. It is a curve. Everyone uses the cheapest chemistry that still does the job adequately.