It also leaves any potential of discussing "chilling effect" like things. You're measurement does nothing to gauge the overall zeitgeist of the time, which would clearly influence the outlook of any researcher who didn't have balls of steel and bulletproof funding.
I agree the author needs more clarity. And the clear thing to say is that "one could easily imagine this type of study in the United States causing problems for the author due to possible accusations of racism".
I do not see those sorts of comments as up to the usual standards of HackerNews. Perhaps to be expected on an article like this, but still they should be discouraged.
What you're asking is not just uncharitable, it doesn't even make sense (even if it was possible).
It's also irrelevant to what the parent said, which is not a quantified claim that such studies are "labelled racist more than 50% of the time", but a casual "usually labelled racist".
In casual conversation "usually" doesn't mean some hard 50% + c, any more so than "often" and "a lot of times".
"Do you have any references for this?" might be less strident.
I don't think the poster needs charity. Clarity is more like it.