The precautionary principle that people, including Nassim Nicholas Taleb, love and treat as some form of wisdom, is actually just a justification for arbitrary acts.
In a given situation for which there's no sufficient knowledge, either A or B can be seen as risky or precautionary measures, there's no way to know except if you have sufficient knowledge.
Someone could reply saying, for example, that the known risk of A is tolerable to the unknown, probably magnitudes bigger, risk of B. Unless you know better or at least have a logical explanation for the risks of B (a thing "scientists" don't have because they notoriously dislike making logical claims), in which case you do know something and is not invoking the precautionary principle anymore, just relying on your logical reasoning – and that can be discussed and questioned by others, undermining your intended usage of the label "precautionary principle" as a magic cover for your actions.