So if we assume a measure is invalid, it is useless to us (as an accurate measure anyway; you already pointed out a possible rhetorical use)?

If you'll forgive my saying it, that seems like more of a tautology about measurements in general than an argument about this specific case. If you have evidence that general intelligence as-measured-by-IQ is invalid, or even evidence that people unfamiliar with the field like Dr Atran or Gould take issue with 'reifying' it, that would be closer to what the original question was looking for.

I realize this comes off as a bit rude, but this particular non sequitur keeps coming up and is becoming a bit of a sore spot.