I'm going to guess the Project Zero article pissed some people off at Apple in a major way, because Apple is right that the headline and the content of the article vastly overstated several aspects about the vulnerabilities. The impression most people would come away with after seeing the headline and skimming the Project Zero article is that most iPhones have been compromised for years. That is emphatically untrue, and so I think it's reasonable for Apple to take a strong tone with this message.