Your argument reinforces my point.
I got the 68% figure from Table 11.
You said, in effect, that the 68% figure isn’t a reliable indicator of how many private certificate holder have IFR ratings because the 68% covers a whole bunch of commercial certificate holders as well. I said that a whole bunch of those commercial certificate holders may have obtained IFR ratings before they obtained their commercial certificates.
Now you’re saying that a bunch of commercial certificate holders don’t hold IFR ratings. If that is correct, it would inexorably follow that the 68% covers a correspondingly greater number of private certificate holders.
Until that 68% figure is ‘sliced and diced’ in a way that can identify the ‘certificate history’ of the holders of IFR ratings, I do not think it’s reasonable to use phrases like “the vast majority” of private pilots don’t have instrument ratings (although I note that you’ve moderated your language to a “minority” do).