If we committed genocide we arguably wouldn’t. That’s the problem with your logic. You’re saying they should have genocided the Cylons because they tried to do it to them. Of course if committing genocide it the kind of act that earns a species genocide will then had they released the virus they would have after the fact earned the genocide done to the humans.
One should always ask questions when one is about to start killing. That’s what separates us from the animals, the ability to understand what we’re doing and figure out if that’s what should be done.