Not a big fan of incest, but, well, I guess I don't really mind it if it's yuri. I always thought this ship was reasonable anyhow since, if I remember correctly (if I'm wrong, I apologize to all you diehard Touhou fans out there) Satori has some curse or something which makes everyone forget her seconds after seeing her and Koishi's the only one who doesn't completely forget her. I don't know if that's true, but, yeah, I think it'd be a nice setup for a loving, tragic romance if it actually is true.