Id say you'd need some very hard surfacing to keep it going for any length of time, and that's the slower moving parts. What about the valve train? On a 3 lobed engine, that cam has to turn 3 times for each one revolution. At 2000 rpm, that cam is doing the work of a regular engine running at 6, which floats the valves on a conventional engine.
I haven't looked at what cam system they use, either 1, 2 or 4, but that's a lot of cam to turn. Even if say, that engine maxed out at 3,000 rpm shaft speed, that valve train would run at a punishing 9,000 rpm. If you've ever built a weekend race engine, it takes some doing to keep the valve train together at those speeds, plus expense, and it doesn't last long. The lobe problem may be overcome with some good metallurgy, but I doubt that the valve train issues can be. Not for a commuter car application at least. With 4 overhead cams, it would run pretty good for a while no doubt. It would be a train wreck if something let go through.
I don't know what the limits are for fuel injectors either, but I can't see them being of any practical use at the potential high rates needed. At say 12,000 firings per min, You may as well use a blower and carb and try to burn as much fuel as you can as it flows through the cylinder, LoL
I think they are counting on this engines torque and lower crank speeds than what I'm thinking of. Maybe in the 1000-1500 speed range max.
What about using it for a two stroke. Yes, not a street engine, but the Jap bike makers still build 2 strokes for racing motors. With a two stroke you get rid of valves, which goes to the point you and others have made that these things have lots of valve openings and closings.