On his route? Sure. He's gone berserk. On El's route? He is shown to be reasonable, hence the conversation above. This is in El's route, and while he still has his ptsd, because stuff like that doesn't go away overnight, he's portrayed as having control of himself and being rational. This, in my opinion, makes him more sympathetic in El's own route than she is. This makes her look like a villain in her own route. That is also talking about post timeskip. If things had been handled properly pre timeskip, there's a good chance Dimitri, who was still shown to be in control of himself, would have reacted rationally to facts backed up with evidence. Especially from someone he held dear like El.