Second, I know from experience how distorted people's interpretations of these situations can be. You seem sure that you judged one example correctly; I think it's more likely that you jumped to a conclusion.
The first thing PG said when teaching me how to moderate HN two years ago was: whatever you do, don't censor stories because they're anti-YC. I think about this every day and try to stick to it. But that doesn't mean that posts like the OP get a free pass just because they say bad things about a YC-funded startup. If we applied the rule that mechanically, we would fail our primary responsibility, which is to keep the quality of HN high. So we do what we can to balance the concerns.