I think that the real existential threat is something which could be described by one word: multipandemic.
That is many simultaneous deadly pandemics, may be organised artificially or because of quick growth of the number of bioterrorists and availability of synthetic biology. I wrote an article about it, but it needs major revision.
Hmm. I could see that being a serious threat, at least a potentially civilization-ending one.
Again though, would you agree that the best way to reduce the risk of this threat is biotech research itself?
I would say that the best protection is as quickly as possible to jump on the higher level, like the creation of nanotech and benevolent AI. But they have their own risks.
It may also apply to biotech research, if protection measures will grow quickly.