It sounds like the label is being assigned to those who don't jump at something, take a ball and run with it, or whatever metaphor you'd like to insert. And the summary reaches a point of "hard to talk to yields lack of resourcefulness." And as evidence, those who weren't hard to talk to were those who closed funding, grabbed users, or some other metric. And those who were hard to talk to were the ones who didn't.
Those who succeeded at something were easy to talk to, but those who didn't succeed at something were more difficult? Not really a surprise, but what's smoke and what's fire? Seems to me there exists the possibility that failure in those areas may be the cause, and hard-to-talk-to was merely a symptom representative of a point in time.
I imagine this is contextual in the relationship of YC to its member companies, but from an outsider's perspective I could see this working out differently.