Is it? The hypothetical technology that allows someone to create an execute a bio weapon must have an understanding of molecular machinery that can also be uses to create a treatment.
Yes, there is probably some overlap in our understanding of biology for disease and cure, but it is a mistake to assume that they will balance each other out.
But in reality you can’t protect from all the possible dangers and, worse, fear-mongering usually ends up doing more bad than good, like when it stopped our switch to nuclear power and kept us burning hydrocarbons thus bringing about Climate Change, another civilization-ending danger.
Living your life cowering in fear is something an individual may elect to do, but a society cannot - our survival as a species is at stake and our chances are slim with the defaults not in our favor. The risk that we’ll miss a game-changing discovery because we’re too afraid of the potential side effects is unacceptable. We owe it to the future and our future generations.
In a free society, preventing and undoing a bioweapon attack or a pandemic is much harder than committing it.
> And considering that our default fate is extinction (by Sun's death if no other means) - we need all the good we can get to avoid that.
“In the long run we are all dead" -- Keynes. But an AGI will likely emerge in the next 5 to 20 years (Geoffrey Hinton said the same) and we'd rather not be dead too soon.