CG?
Ive got about 1500 hrs in this machine, and I can tell you that it's very easy to load with the cg out the back door. Some Carriers use a pogo stick at the back. If you can't get it out when you've finished loading, it usually means someone's telling porkies on the weight and balance. As someone else said, the excessive nose oleo extension can give you a clue, the bigger step up into the plane, and the fact that it's like taxiing a taildragger all tell you something.
All of this can only make a bad situation worse. I don't think any plane that could be taxied could be completely uncontrollable on rotation with a functioning elevator -- as long as you are sitting close enough to the controls.
So , IMHO CG made it worse, but could not have been the cause.
Wrong place at wrong time, I guess.
A control check should be made in every plane before every takeoff. I only started to do it EVERY time when I started flying jets. Until then, it was always a first flight of the day thing.
It's a shame that an accident has to happen before we take notice of these small but sometimes very important things.