Oh hey, that's a good point. [He's just been eavesdropping this conversation because he heard his name come up--]

It's totally believable that Pigtails and Diamonds could be accomplices if Diamonds meant to get away before anything exploded, and Looking Glass just set it off earlier than she wanted. All of this "she wouldn't risk her life like that" or "Pigtails wouldn't let her risk her life or hurt her friends" doesn't mean anything if they never actually intended to, and it just accidentally happened that way.