I can stare at the code all I want and still be no closer to knowing how rails performs under load, or how much memory it leaks. That isn't just about the code, it's about behavioral interactions with the OS, level of traffic, other layers in the stack. To address those issues I could run a million performance evaluation experiments, or I could try to gauge how the community is doing, who's using it that is kinda in the same situation as me, and what issue's they're dealing with. And I refuse to believe you don't do the same.
He's not talking about what words DHH uses in a blog. He's talking about DHH's credibility in saying rails was production-ready. That is relevant to platform choices.