I'm pretty sure those machines still run WinXP at best ;)

And yes that's exactly what I said. You still can run Linux on a 486 for this special edge cases, it's just that the Linux Kernel team will no longer provide the service for maintaining it. If it is such an important thing for crucial industry machines, they can definitely pay someone patching it back in.

For the overwhelmingly majority of Linux use cases it's not a concern anymore. So why should they do the extra work, instead of spending the time elsewhere?