Even if the green, yellow and red -including the white/ black text on top of the coloured fields- would disappear completely, a catchy and explicit description of each release is still underneath in black on white. Out of curiosity, what problems would you envision with the mockup page above - respectively how would you solve them in a better way?
While hard to tell from a mockup image, the resulting page shouldn't pose much of a problem to screenreaders either - no fuzz, no reliance on pixel images.
It is very hard for designers not specifically trained for accessibility issues to notice potential problems (early enough or at all), so I'm really curious what would be an issue with the mockup above? I wouldn't expect the directory-browsing enabled representation of the download site to go away either, as the above seems to me more targeted at providing a shortcut to the casual user, rather than replacing https://downloads.openwrt.org/ altogether.
 and at least the two colour blindless simulators I could locate on the web suggests that in either way the text remains fully readable, just the surrounding colours go through several different permutations (depending on the chosen filtering for deutanopia, protanopia, tritanopia or achromatopsia) - weird, but nothing that should surprise or confuse a person with these conditions.