We are not home just go away

Why is this so strange? This makes perfect sense. They know that the Human race is watching and they just dimed the light to tell us that they are not home and that we should go away

http://www.scientificamerican.com/article/kepler-s-alien-megastructure-star-just-got-weirder/?WT.mc_id=SA_FB_SPC_NEWS