Sure, I'm largely aware of how colorblindness works (my father is colorblind and my friend is colorblind and I've discussed it multiple times with each). I'm really looking for whether experiencially you, or the root comment, have experienced good color schemes that work well within the constraints you impose, and whether that alters the statement slightly from "it should not default to color" to "it should not default to color unless done well".
I understand that the answer may be different for different people in somewhat non-subjective ways, since there are different types of colorblindness.
In the case of text that means asking the question: does removing all color remove any information? If the answer is no, then a colorblind individual can use other cues. (While my prior post focused upon legibility, two different colors may look like the same color to me even when the text is perfectly legible.)
I would also suggest keeping the number of colors used to a minimum. More color combinations means more opportunities for problems and more difficulty in resolving those problems by setting a custom palette.
Finally, only use color when it adds value. The use of color to highlight different file types was useful. (The file extension still existed as a cue, which is great.) The use of color to highlight columns is just asking for trouble without adding value. It is not adding value because all of the elements in a column are the same color anyhow, so it adds the risk of reduced legibility without highlighting anything in particular.
I understand that the answer may be different for different people in somewhat non-subjective ways, since there are different types of colorblindness.