Yes more power is required from vertical to forward transitioning.
RE: You seem to be assuming hover at 36k feet where it would seem that would be for forward flight. Not being an aeronautical engineer have read some of what Moller has designed, and the hover part from ground to forward movement requires the most power. There will be lift form from the wings. He has white papers on much of this you are seriously interested
Answer: Even if we assume hovering at 5,000 feet the air pressure is 12.23 psi down from 14.694 psi.
The engine power will be reduced to 12.23/14.694 = 83.23% x 720 hp = 600 hp
If the gross weight is 2,400 pounds and the load is 720 pounds = 3,120. The required lifting ratio is 3,120 / 600 = 5.2 pounds per engine hp.
The surface area of the craft with the wings seems to be around 152 square feet. Thus the minimum forward velocity to sustain forward flight would be around 97 miles per hour.
The reason I am saying these things is that the rotary engine can only provide enough power that rides on the maximum required power threshold. Transitions from vertical to horizontal and back would be a very delicate task. A more powerful engine is needed for any flying car to be more nimble like having the essence of a dragonfly's movements. This would allow it to sustain the several forces acting upon it and provide better performance, maneuverability and safety. To be realistic in order to do this such engine would have to have a power output (density) of roughly 2.5 to 3x of this rotary engine.