To believe what Edea is saying, though, we must assume many things. We must assume that Missile was converted, we must assume that one of the VIPs was able to train him, we must assume that such training could occur overnight, we must assume that he was capable of carrying out such a complicated and malicious plot, and we must assume that Edea is entirely innocent and that the VIPs are trying to frame her.

To believe what we already believed, all we must assume is that Missile did not understand everything that was happening before, and that he acted after Gundam Tanaka explained the situation to him.

One of these options seems much more likely to me.