It's much easier to create a poison than a medicine. The things that would harm biological life vastly outnumber things that restore health. So just because Novartis didn't succeed at creating an incredibly precise and specific medication does not mean all the AI in the world can't make a crude bio-agent.

And yet we aren't extinct, whether by someone's design or accident. Heck we don't have significant deaths occurring over time due to biological poisons. Most deaths at still overwhelmingly via conventional weapons.