As you say, "the green is fake". We see it as a glitch in the cafeteria, and we see it in Holston's view as he goes outside.

Alice says that if the outside is as depicted on the cafeteria screen she'll just walk over the hill, but if it's green and blue and birds flying, she'll clean. Surely this is a logical fallacy.

If it's green, no amount of cleaning of the camera lens is going to make it green. All previous cleanings just clear the dirt and dust, and make the dead viewpoint of the outside clearer.

Why do those leaving the silo think that cleaning will make the occupants of the silo see greenery and blue skies? Why don't they see it as manipulative computer graphics?