Actually green makes sense for "electronic" binoculars. Lots of night vision scopes and such are displayed in varying shades of green, hence the so-called "green screen warfare" of modern times (mainly because the M1A2's CITV display is all green).
Red and green are both colours that you see in different kinds of thermal imaging. I've never seen a pure yellow scope before, although you see yellowish colours sometimes against red/orange, or blue/green.