The post we're commenting on addresses this: this concern is why the guideline is enforced only as a community norm, not with code.
I mean, I don't disagree: I think this changes absolutely nothing. If anything it's a renewal of the old guidelines, not an addition to them.
I suppose I think there's some ambiguity into what is intended, and there's therefore some investigation into HN's relationship with negativity going on.
There's a kneejerk reaction to view this as an attempt to prevent people like me from spouting their usual hostility towards the tech scene, and I demand the right to be booed off stage!