Doesn't really rule out anything. If he played around with his memories, the first couple of chapters all could have been false memories.
I was on "Is this Satou?" train for most of the chapter, primarily because that would have been an interesting twist, whereas this being Shin becomes more "Eh, yeah, Shin was... er, that guy? Some tertiary character that was kinda important but not really and will cease to be a factor in a few chapters?"