If Bran is truly a godlike creature, then the deaths of thousands don't disturb him. It's just the way it has to be. I mean people die every day, some in horrible ways, and God allows it to happen.
But then, seeing as how he didn't automatically know where Drogon was, I don't think he's all-seeing like that. That's where the show failed, at explaining Bran's powers. Of course D&D never really cared about Bran, so there's that.