Dude is a turbo autist, the entire framing of the case has come from his perspective and severely lacking information. All the information that he's filled out so far has decreased the possibility of his original hypothesis being possible.
It's pretty entertaining, the neuroticism level of all the girls is so high and they're all hot too so yeah. I think the case is also helping him distract from how horny he generally is too, which is fair. Them sisters are super gooners.