It's impossible to hold a weapon 100% still in real life. And currently, having zero scope sway when using bipods on LMG's, snipers and even regular weapons when not suppressed or out of breath seems a bit too OP. Someone with a fortified position and bipod should have an advantage over incoming moving enemies, but 100% accuracy and zero sway is a tad bit too much, I feel. Insurgency 2 had sway at all times, so this seems to be an intentional design change.
I realize the removal of scope sway when ADS'ing and holding breath on higher zoomed scopes is likely for the imminent console release due to joysticks, but introducing a little bit like in Insurgency 2 I think benefits the game both in realism and patience. Having to wait to line up your shot in Insurgency 2 with scopes 2x and above made the kill so worth it.
This was implemented in Insurgency, and was curious if it would make a return in Sandstorm. Right now, zooming in with a scope greater than a 2x on a bi-pod deployed weapon has no idle scope sway. Though, I'm sure this may be for consoles since idle scope sway might be too much to compensate for with a joystick at a moments notice.