Hank Pym (AKA Hulkling in disguise) purposefully programmed Ragnarok to kill.Hulkling is a half-Skrull infiltrator. He was always on Captain America's side, as were all the Young Avengers. Is it so far to claim he may have actually reprogrammed the clone Thor to be lethal? Tony says it was a glitch, but maybe it was purposeful. That would certainly kick the war into higher gear. Theoretically, Hulkling may have instigated the entire tragedy that follows. Certainly an Alternative Character Interpretation.
Tonys actions are being influenced by Ultron.Immediately after Civil War, its revealed that Tonys body has been infected by Ultron who uses Tonys Extremis-based body to remold it into a biomechanical version of the Wasp. Throughout the war, Tony creates a biomechanical clone of Thor subservient to himself, tries to lock up superheroes in the Negative Zone, and creates a nanite controlled super villain army. If Ultron was controlling Tony during the war, these all seem like exactly the things Ultron would do pave the way for his eventual takeover. Hes hoping to push half the heroes off-world, build himself an easily controlled Masters of Evil to take on the rest, and a new body with the powers of the Avengers most powerful member to take. Hercs destruction of Ragnarok, the overturning of the 42, and the Thunderbolts being shunted off to Colorado following the NYC battle caused him to scrap his original plan.