It's good to see people trying but I'm not convinced. Though, this may be a viable alternative if there is an industrial shortage of brass or copper.

The author stated that the two sections start to separate when bullets are pulled. I wonder what would happen after a long time of carry or storage where they are subjected to repeated and prolonged jostling.

The author points out some advantages to having the front section made of steel. Can those cartridges end up rusting to the chamber if carried loaded for days or weeks at a time? Will the steel cause greater wear of chambers, feed ramps, and maybe even magazine lips? Commercially available ammunition loaded in steel cases is lacquer or plastic coated for a reason.

The rear section is nickel plated aluminum. Aluminum corrodes very easily and quickly. It wouldn't take much to make the aluminum in the cases turn bad if there was any sort of failure in the nickel plating, even a pinhole. I wonder if the extractor can cause such a failure in the plating if a round is loaded, not fired, then extracted.

The author also says the cases cost less than buying brass cases. I don't load 9mm cartridges but if I did I could buy once-fired for only 9¢ a case.

I don't know the answers to all the questions but I would like to know before using the cases.

Traditional steel cases are laquered because they are steel, not stainless steel.
I could see a very simple die setup to re-establish the separating cases back to spec if bullet pulling was causing them to gap.
I wonder why they opted for the plated aluminum for the base as that part seems to be the point of most concern. I can't imagine that producing a nickel plated aluminum base is cheaper or easier than using say, brass, for the base...

Why?