That’s his astrophoto course, obviously. Plus, focus stacking is not HDR.
FTR you can find very similar processing from many others, e.g., Nick Page, Mads Iverson, Nigel Danson, Michael Shainblum, Andy Hutchinson, James Popsys, Adam Gibbs, etc., etc. It’s a standard technique, by and large. But if you doubt, ask Will - He’s responsive.
I think you might be wise to watch for a while before you declare him and “99% of photographers” to be liars. Does that include everyone here as well?
The point is the technique and how it can be implemented in ART. Whether it involves one image, compositing or whatever is ultimately irrelevant – it’s the image that matters. I don’t believe HDR is required for this technique (I’ve come too close myself before without HDR). Modern cameras can certainly handle the dynamic range, even my low-end DSLR.