The attack pattern also makes no sense for a criminal organization with this level of access. Why wouldn't you go after resources you could trivially monetize or data you would want to know about like customer data, IP, financial resources, law enforcement, etc? Reading government emails seems like a waste of time unless you are trying to resell the intelligence to interested parties. Going after FireEye red team tools seems like a very high risk waste of time.
Lastly, you're taking on American intelligence with above the wire capabilities. You're telling me a group of this size has the opsec capabilities to evade the NSA? No one made a mistake?