That’s not an apples to apples test because of how greyscale is computed. Try swapping the blue and green channels rather than converting to greyscale.
I think for a proper comparison, you would need to swap them by perceived brightness (luminance), not just the RGB value. You can't do that here because the green channel in this image is out of the possible range of luminance you can achieve with blue (in any standard color space, probably).
Which really illustrates why TFA doesn't make any sense- our eyes are less sensitive to blue, so the contrast provided by max RGB value blue is going to be completely drowned out by red and green if the source of your contrast is white on black.
Here's what it looks like with all channels shifted to have the same luminance: https://i.imgur.com/AnKNdfX.jpg - note it is perhaps a little softer as the peak brightness is closer to black.
They're all clearly fuzzy in comparison to the un-blurred image. The answer to "why we're blind to the color blue" is not chromatic aberration (although it could be a contributing factor, maybe even why we have less blue receptors), it's that we're less sensitive to blue and therefore contrast is usually defined by red and green.
