I don't why such a robot should be impossible, but I don't think the state of the art has reached that point as of yet.
Most humans have an intuitive "feel" for how vertebrates, not just other humans, are supposed to move. I think that the creepiness of these robots comes at least partly from the fact that they violate our instinctual preconceptions regarding how quadrupeds are to supposed to look and act. The robot is obviously performing a balancing act as it moves about, something we normally associate only with organic beings, yet it is clearly mechanical in appearance.
That's before considering the provenance of the robot itself, produced by the kind of technology-oriented corporations that have already brought massive social and economic disruption. That might also be a factor influencing peoples' reactions.