Except that the blades can't reach the fin and if you bend down a blade to the tail boom, that point is exactly where it would hit.
A driveshaft failure could happen anywhere in the length theoretically but most probably at a joint/coupling.
The driveshaft has clearly been sliced rather than ripped and the left hand side of the boom is bent in slightly whilst the right is torn outwards.
I really can't think what else could cause that damage other than a MR blade strike.
The T&B calls up the thought of a maintenance error.
I hope the investigation team has better quality witnesses than this guy...
"I hear this engine thrust really loud and then something exploded," Megerdichian said. "That piece of the rudder came out of the helicopter, flipped sideways and another explosion happened and shot the helicopter forward. Blades went flyin'. That's when I tried to run back because there was parts everywhere comin' down from the air, from the sky. I mean there was everything in the sky."