If, by this you mean they would not be able to detect a sniper using iron sights then yeah, I think that's true. One thing about snipers is they typically are further away since they are wanting to live through their attack. but if you had someone well hidden within 200yds, that's easily done with the Mk1 eyeball. Though hitting the head rather than just the target is far more challenging.
Something else, if the scope was electronic and not optical, it would be possible to potentially tie in an electronic scope mounted on a building and fed through an electronic feed so you could aim by computer screen and servo.
Humans are inventive. Every one of these points always gets a counterpoint.