It sounds unlikley as explained, If the cut was 50% the rotors would have made contact with the T/R drive shaft an item that is really quite substanstial despite it being Robinson, plus the tail boom of the R44 is a monocoque and would possibly have sagged upon impact of Hard landing, so rotors would also be badly damaged.
It is quite possible however to have a start up tail cone strike without severing the metal, but that sort of impact would also put the damage out of limits and cause a grounding until that section of cone was replaced, Rotor inspected and tested along with M/gbox for shock impact
On the latter I have witnessed that sort of strike firsthand, after the Wally pilot had flown back to his point of T/o after his first land away in the SFH R44 !
Vfr