You're missing the emphasis on silently. They're just minding their own business, feeling around for the handle, and then suddenly, WOOSH, they hear sound of a door opening and non-equilibrium air pressures adjusting. They get on the defensive expecting someone to pass through the other side, but when all is silent they cautiously enter wondering what mysterious force caused the door to open. Was it just the wind? An inconsistently functioning motion detector? Or... the deeds of a mysterious hero? Provided no one else is witness, you will become almost godly to them. Maybe they hear retreating footsteps as the door closed behind them, maybe they brush up against your clothing, but to them, it would be like catching a glimpse of Spiderman as he swings into the metropolitan horizon. They will begin to worship you, but if you are of modest and pure intentions, you will never tell them your true identity.