Shiikawa dumped Satoko in highschool, seems like he remembered everything about her habits, got engaged right in her face, got disengaged sometime later still being salty what happened over 15 years later.
He really doesn't look at Satoko as "human being", sure he does act like a moral compass, but him acting like that makes him a huge dick.
What's worse, Shiikawa and Motoki remember well how they banished Satoko and the reason they thought it was true.