If you look at the design of the aircraft, you can clearly see that the main gear are way aft of the center of lift.
Because of that configuration, the excessive downward force required by the elevator to cause the plane to raise the nose with the pivot point being the (too far aft) main gear would guarantee pitch-up once the wing generated lift and the "pivot point" changed from the main gear to the center of lift.
If accurate, this would not be a unique accident sequence.
This was the situation with the crash, on its first flight, of an experimental delta-wing aircraft (Flint, Michigan, almost 50 years ago). It had a pusher prop, with MLG well aft to give ground clearance. It had a very long takeoff roll, then a rapid pitchup and stall.