I am really sorry to see this happen to such an iconic plane, the type that Amelia Earhart disappeared in. I am glad everyone inside was ok. To me this accident has nothing to do with P factor or gyroscopic precession. The aircraft was under good control until just after the tail wheel touched down. It then veered rapidly left. This is about the time the brakes would have been applied, As mentioned above it could have been a locked (left) brake but if this was the case it would have continued turning left whereas it straightened up after it turned towards the hangar. It is more likely to have been a failure of the right brake so when left brake only was applied it veered left. To increase the left braking would have aggravated the groundloop leaving the pilot with very few options.
I hope it can be repaired ok. Good luck guys.