Shinji kissed a girl, he's a normie
Satou has friends and a girl that talks to him, he's a normie
Nii-san is in a rural area with only his sisters and doesn't talk. He's a robot.
I was going to post this.
Maybe in the anime adaptation, but in the light novel he decided on his own time to download as much loli as he could to prove that he wasn't attracted to children because obviously if he wasn't a lolicon he would eventually be repulsed by underage girls.