I considered that for a moment, but ask yourself: If a murderer was after your girlfriend, would you use her as a bait with no backing from the police or anybody, in a location as unsecure as the one in this ep?
It just feels so unbelievable that Satoru would make a mistake this gross after telling himself this is his last chance and he'll do anything to save Hinazuki. That's why I don't know what to think.
It would be awesome if it was Satoru's mom, but the intruder looked like a man.