Nah. They left corpses and everything. They made it so that it seemed like a early strike team/first wave. The plan being humanity unite to prepeare for oncoming threat. The book goes on to explain that "Even this, will fall apart. One day, they will realize the aliens aren't coming." And there is a shot of Rorsarchs notebook having made it a some news office, basicly giving the ending a poignant "Oh shit" ending. Basicly it was very layered and well executed. The comic is a goddamn masterpiece and likely the best thing I have read comic wise.