Pure speculation, but here is a possible scenario, after all this is a rumour network...
Elevator trim tab failure at high speed causes extreme high 'g' pitch up, pilot blacks out, slumps forwards, 'g' causes tailwheel unlock, aircraft impacts at full power.
Notice that in the pictures of the aircraft just before impact that the pilot's helmet is not visible, the elevator trim tab is damaged and the tailwheel is extended.
Details of the aircraft in normal configuration:
Galloping Ghost Specifications | Florida's Premier Airpark - Leeward Air Ranch