I shake my head when a project is all modelling and no physical prototype. It's not that hard or tragically expensive to make a one off. If you truly believe in it, get one made (or make it yourself). On the other hand, if the projects main goal is to chase money instead of a working product, modeling is a great way to go as you can just keep holding the carrot out with more modelling and you never actually get to the physical prototype that proves it doesn't work as described. I see in the video they had a prototype but it was running on compressed air. It wasn't self-sustaining. You can make almost any design rotate with enough compressed air. If it needs compressed air to run, efficiency will be completely in the crapper (assuming it could make enough power to run its own compressor).
No seals isn't a killer, you can get away without seals in certain applications. Turbines and some superchargers don't have perimeter seals. As for temperature, it's theoretically pretty low mass and not physically large. If you can get it to start it should come up to temp pretty quickly and expand to shrink the inter-rotor clearance (or if they want to get really fancy, with proper material selection they can make case and rotor expansion cancel each other out so clearance is maintained).
Sadly the future of ICE is as a historical oddity although it will remain the primary motive power in service for a very long time (especially in some applications like planes or long distance trains).