I guess landing engine-out would be no problem as long as you keep the nose (prow?) up
Hmmm, I don't agree...
The engine is doing three things for you on a hovercraft, and by extension, this machine: Provides thrust, pressure for cushion lift, and airflow over the rudders for directional control.
Loosing any one of these can be a problem, all three simultainiously - loss of control is likely. When a hovercraft is not producing cushion pressure, the drag relative to the surface, be it water or ground, is very high. If you touch down at high speed, with high friction, it's going to be bad (particularly with no seat belt). Worse, with no real directional control, nothing really prevents you touching down going sideways, which is certain to result in a rollover. Even a hovercraft in the normal sense, flying on cushion, is at risk of rollover while moving sideways, if the engine stops.
It looks like great fun, 'till something goes wrong, and someone is hurt. Then people line up to ask: "How could they be allowed to fly such a thing?". Then someone makes a regulation about it, and everyone cries about more regulation. Then someone dreams up another type of machine in which to hurt themselves, and the cycle repeats itself.
It's not that I'm against innovation, but when it is not accompanied by some mitigation of risk, a whole (or in this case, more than one) industry gets painted with a black mark, and more heavily regulated.
There are a lot of design standards out there, which when followed, are very likely to result in a product which is acceptably safe to our society. As has been said so well,
"Regulation is for the guidance of wise men, and the obedience of fools"
This is why....