Taking over even one person for part of the time is objectionable in human exchanges. That's fraud or kidnapping or blackmail or the like. This happens with words and images on screens among humans every day. Convince a mob that bad people need to be punished and watch it happen. No bad people needed, only a mob. That is a Turing compliant big mess - demonstrated to work among humans and if a machine did it the effect would be the same. Again, messing up one person is objectionable enough, no global disaster needed to make the issue important.