> what should be done about open weight bioweapon and cyber-offense capabilities?

If the model is capable of it, then it was in the model's training data, which means it was on the internet or published in books made available for consumption. So if any member of the public could have gotten their hands on that information, so be it. If the knowledge was too dangerous for public access, then it should have been highly classified and never found its way into the training data. Tough shit, frankly.