I agree with the conclusion that given enough time, all secrets will leak. One day, there will be freely available PDF “How to make an Ebola virus at home for less than $100”. When that day comes, I hope we will have some good defense against it, otherwise we are screwed. I just don’t see why I should wish for that day to come as soon as possible. We do not have the defense yet. Heck, we couldn’t defend even against Covid.
Destruction is usually easier than building useful things. Attack is often more efficient than defense, even more so when it has the advantage of surprise. Bad things happen, and we often do not have a reliable protection against them. For example, murder exists in all societies. We try to eliminate some bad actions by punishing them afterwards. Which is quite useless if the bad actor is willing to die in the process. (You cannot use the threat of prison against a suicide bomber.)
The thing that protects the civilization now is mere statistics. Consider the fact that most people are completely vulnerable to murder. Unless you are hiding, or surrounded by bodyguards, killing you would most likely be trivial. So why don’t most people get murdered? It’s because people willing to murder are quite rare, and even if they succeed for the first time, they often get caught afterwards, so the average number of victims per murderer is quite small. Mass murderers have more victims, but they are even more rare in the population.
This will change if we get more efficient murder tools. If a tool is capable of killing N victims, and 1 in M people is willing and capable of obtaining and using it, civilization calls apart when N ≅ M. Knives and guns have low N. Nukes have very high M. “How to make an Ebola virus at home for less than $100” has high N and not too high M.