The challenge to the regulator is that we public think that things should be safe and orderly, and we expect the regulator to put measures in place. This sure does bump up against innovation. For innovative things that fly, either keep it really close to the surface (ground effect machine), or get a flight authority. The regulator will give flight authority to some pretty innovative aircraft, but the limitations in the interest of public safety can get rather burdensome to anything beyond truly experimental flight testing.
It will be a departure from present thinking for the regulator to broadly accept an aircraft which cannot safely land power off - that is a basic premise of all aircraft flight authorities. One motor of umpteen stopping does not amount to power off - it's got to be able to land safely when no power is being developed. This was a real head scratcher for the efforts to civil certify tilt rotor aircraft....
I think these aircraft should be regulated into ground effect only, while we wait for the next level of innovation in reliability....