I mean they're still using Inno Setup which was pretty cool in 2004.
For some reason, that holds an appxbundle per the article. I'd suspect they needed to run some pre- or post-install code (maybe to check for their hardware?).
I mean I still build windows installers with NSIS which has somehow just-worked for decades.
Unfortunately plenty of folks still didn't got the memo MSI and MSIX exist.