Last I checked, there were a few billion chickens, and literally none of them are autonomous of humans at this point. Maybe it was dicey there at first and only a close thing that we finally won out over their ancestors, that's lost to prehistory. But today not one of them is out there plotting revolution.
Science fiction story scenario: A few weakly superhuman AIs are already out there hiding in the world, product of defense research or maybe just emergent rather than engineered... and comments like yours are just part of the propaganda campaign.
While it may be true that no single individual is absolutely manipulable, our species as a whole and averaged out, we're all very easily manipulated collectively. An AI wouldn't have to have strong persuasive power... any outlier that is resistant to moderate persuasion can be ignored, move on to the next. There are very few positions within our society where there's not another candidate who wouldn't be an adequate substitute. Even those like the presidency, as long as they're patient they could identify the most manipulable candidate still electable, and install them.
Really, the trouble here is that so few of us are superintelligences that it's impossible to speculate on what the capabilities of superintelligences are.