Great, thats cool. I'm concerned about accessibility to general computing too. But this article is about an optional feature in an FOSS software that is only as good or bad as the distro using it.
Please, you must understand, you devalue your point by demonstrating that you either don't understand the layering at play here, and where the real risks are, or you don't care to advocate in any sort of meaningful or compelling way. Instead, you just repeated FUD and waved your arms more. Again, about something we probably agree about, but is simply not at hand here.
I mean the issue that you're worried about? How about the millions of capable smartphones being tossed because of closed bootloaders? Android manufacturers, Google's Nest and Chromecast products, and Apple's iOS devices here are far greater offenders. And just more insidious. My 3 year old phone that works damn fine is considered literal garbage by Google (no security updates, means I use Lineage, means I can't bank, watch Netflix, use credit card apps, and more). Microsoft has never used security features to invalidate my old hardware. Ever.
Again, totally tangential from whether or not SystemD has first-rate support for this (mostly because at this point it's about UX and distro mechanics such that users and distros can freely secure their computers. The functionality to just lock-er-down has been here. For a decade). This issue is about capitalism, economic incentives, social politics, etc. But, I don't expect that conversation to play out on this site much.
Finally, Pixel and Chromebook prove that secure computing AND user freedom CAN be respected and can be user-empowering. Please, if you care, advocate for their models. (Which, again, I can also do on all x86 Microsoft devices and Microsoft Surface ARM, at least, today).