Warwick's Blood Scent

I would like to understand why, oh why, Warwick's E ability, Blood Scent, does NOT allow him to see through invisibility on weakened champions. One would surmise that a blood sniffing werewolf could not possibly care less that you are invisible. I mean he sees(smells) through brush and around obstacles and over unpassable terrain, so WHY can you not see through a Wukong decoy? Hmm? My salt may be quite strong as I write this but still... it seems to be a valid point.