His tweet before that video was "We figured out how to design rocket parts just w hand movements through the air (seriously). Now need a high frame rate holograph generator. Will post video next week of designing a rocket part with hand gestures & then immediately printing it in titanium". That's really disingenuous. First of all, it looks like a typical demo made by an intern and some toys. Second, mechanical engineers don't need or want that type of interface. Actually manipulating and rotating CAD is such a small part of the process the time sink (aside from all the design and documentation aside from CAD) is adding dimensions and relations to geometry and relations. This video is the equivalent of a software developer's manager showing off a visual programming language and declaring text-based languages and keyboards are obsolete.
Google actually one-upped Leap Motion with Project Soli that's in the new Pixel phones It can track minute finger gestures in a much smaller form factor using radar. It similarly doesn't have any killer app that actually makes it useful for much of anything.
I had one when they first came out and while the tracking accuracy was quite good, it wasn't good enough for doing any precision work. Every so often the tracking would skip and glitch.
I guess actually swinging your hands around in air like Tom Cruise in Minority Report was too tiring for most people. I wish Apple had bought them and integrated them into the macbooks instead of the touchbar.
[0]: https://en.wikipedia.org/wiki/Leap_Motion
[1]: https://www.ultraleap.com/product/leap-motion-controller/