I think you mightve confused the definition Yandere, they are mostly obsessed with someone, because they love them, and they are usually mentally unstable, that they would kill anyone who stands in their way, so they can be with the person they love
Yandere is a Psychopathic form which is what Saiko means in Japanese, so no I don't think he messed up. I think he was refering to how Yandere's are Psychotic, like the girl, so the name Psychotic Stalker (Saiko no Sutoka) was born
