Change for the sake of change is so dumb. I’m tired of pointless UI changes every so many years because some middle manager and their designers need to wow some dumb exec to get a promotion and they do so just by rearranging all the existing functionality because the product itself is already a complete solution that doesn’t actually need a new version. Sadly, this mentality even creeps into FOSS spaces. Canonical and Ubuntu wanting to reinvent the wheel with Unity, Mir, Snap, etc. GNOME radically changing their UI all the time.
If you read the article, it is indeed full Linux because the 4004 is running a MIPS emulator that provides the necessary memory management features. Pretty much all of the “run Linux on some old chip incapable of running Linux” projects achieve it via emulating a more featured architecture that Linux supports, not by somehow compiling Linux to natively run on a 4 bit, MMU-less architecture.