Loads this violent could also fail the tail boom if it was the same source of loads that contributed to both structural failures with the boom failing first, then the roof structure.
Or perhaps the other way around. I was involved in the investigation of a [not Bell] crash, where the tail rotor had a failure first, and the resulting vibration was enough that the tailboom departed the main fuselage. In that case, the remainder of the helicopter hit the ground before more parts departed, but the forces were extreme on the main fuselage after the tailboom departed. Perhaps, on the Bell, such forces could be sufficient to rip the top deck/transmission attach points off.