Theo's mind wasn't really at it's best these days, and trying to protect his psyche from further damage was difficult when memories of what had caused it to collapse in the first place were brought up. It was made further problematic by the fact that there were so many triggers for the multiple bad things that Theo's now poorly-shored mind was trying to forget that anything that seemed utterly unrelated could set him off at any time.
His mind reacted by just shutting down and he did so, eyes unseeing and his body unresponsive.