I can't build (for example) a doomsday device that will eliminate all life on Earth. I still think I should be allowed to disagree with the building of one.
Alright, let's ignore research because it complicates the matter. Correct doomsday device scenario to "I've never carried out genocide, but I still think I should be able to disagree with it."
But you shouldn't have the right to block research that could hypothetically one day lay the groundwork for building such a device. Otherwise let's shut all the physics labs tomorrow.