I mean he seems to be a highly functional sociopath. And sociopaths tend to be antisocial however they can feel little empathy and care for those who matter to them unlike psychopaths. He mostly only acts or does something for his own benefit and never anyone else though, including forming relationships he can use later on. And sociopaths especially high functional ones like ayanokouji are scary becuase they can feel.
It is really not that hard to understand. He was threatened by Chabashira, so he was forced to go full on survival instinct. Ayanokouji clearly wants to experience a normal life, but his situation made him unable to. Also wanting to have friends, while is a genuine desire of his, is stunted by the teaching of the white room, where he must see everything as tools to survive. Ayanokouji is one where his disposition and desire is at constant conflict due to his upbringing.
It's weird to see Ayanokouji quite expressive in the manga after watching the anime. I am curious about one thing tho, at the end of season 1, Ayanokouji said that he didn't view anyone as his ally and that humans just tools. Isn't it quite a hypocrite to say since he was looking forward to get friends when the school just started? And he was the one who approached Suzune at the beginning. I do notice him getting much colder and calculative as the episodes going, but I think it's just weird?