My preference would be something CSS or HTML based where if JS is off it still displays an image. I am not a super web developer or anything, but how about a fi

My preference would be something CSS or HTML based where if JS is off it still displays an image. I am not a super web developer or anything, but how about a fixed-size <div> block with the background set to the low-resolution version that contains the high-resolution version? Or just both images, stacked on top of one another with the high-resolution version positioned higher in the z-stack? Looks like they didn't even add a <noscript> tag (though generally I think uMatrix doesn't play nicely with noscript because scripting is selectively disabled, not entirely disabled), which would be at least a token effort towards alleviating the problem.