I guess Hori had always had a hunch that Miyamura did all that to subconsciously self-harm, at least initially. I mean, I do see why people are mad at her for getting angry, but coming from someone who used to be in Miyamura's state, I can sometimes appreciate someone getting angry at me instead of showing pity & "let me do what I like" ¯\_(ツ)_/¯