The fundamental problem with loosing GMOs into the environment is that there's no plan B for screwing up the earth or your health, so we have to be extra, extra conservative. Even if only 1 in a million GMOs turn out to have disastrous consequences, given enough development and use, eventually we will create something with unforeseen consequences that passes whatever standards for safety we have. But given the replicable nature of biology, it will be everyone's problem instead of a localized disaster.
The people claiming we have sufficient scientific evidence for GMOs don't understand this key point: our usual standards for evidence of safety must be orders of magnitude higher to risk the planet.
PP is used when a system, in this case the humanity, is at risk of total failure, i.e. ruin.
Yet Taleb has published several, apparently with no concern whatsoever about his own precautionary principle.