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.
The blog post comment that you refer to seems to reflect a poor thought process. However, mine has a little more reasoning behind it.
Well, all the code is available, right? You should base your decisions on the design and implementation of Rails, not on one of the author's blog. This is a really scary pattern emerging that I've noticed. It seems like people want to base their infrastructure decisions on things that don't matter. "Well, I would use $foo, but the website doesn't look very nice." "$foo seems nice, but the main author can be mean." If this is how you make IT decisions, I pity you.
(A while back, someone posted to my blog a comment that read, "Because you were so mean on CPAN Ratings, I've suggested to my clients that they use PHP instead of Catalyst." That doesn't seem like a very sound way of evaluating infrastructure decisions, especially since I am not the author of Catalyst. If they want to make more work for themselves because they don't like me, all I can do is point and laugh. Clearly I'm mentally ill, though.)