That's as silly as it is logical. Time looks directionless on the molecular level, where motion is perfectly reversible. But nothing is so perfect in our larger scale of sensory awareness. Here in the visible world the past cannot be undone. Time's arrow flies from past to future.
Air never flows back into the tank.
Boltzmann turned superb mathematics on the question. He showed how rules of averaging won't let such a reversal occur. In any large collection of molecules, disorder continues increasing after you reverse the motions. The gas must keep flowing out. The trouble is, his math didn't say why reversed molecular motions won't reverse history.