And yes, he frames what he says as an exploration of Carlyle's ideas, but he's not just saying "Carlyle said this; isn't that interesting"; he's presenting his own opinions too.
As for whether believing that white people are (statistically, on balance) cleverer than black people makes you a "racist" -- which, again, was not what I was referring to above: it's really a question about the definition of "racist", and disputes over definitions tend to be unfruitful. For what it's worth, I would not call anyone a racist merely for believing that proposition.
From what I saw, that's exactly what I think he's saying, perhaps I missed something you saw, perhaps I didn't. It seems the conversation has pretty much run its course now, so shall we agree to disagree?
If you've read that and come to the conclusion that the author is a racist, I can explain what you've missed in one word: intent.
The author is exploring ideas. The early parts of the blog post set this exploratory tone quite clearly by framing Carlyle not as someone with absolute moral authority, but as an original thinker, a counterbalance to his time and our time. By exploring Carlyle's ideas the idea is to examine commonly held assumptions. It's an intellectual exercise, and a healthy one at that.
As for the 'racist' comments, I don't think they're racist. The 'racist' argument being made can be summarised as... 'The idea that genetic diversity is equally balanced across all races has not been proven, it's an assumption made to further a political cause. However, even if there are genetic traits more closely associated with one race over the others, it does not make those other races inferior. This line of reasoning exposes another form of oppression, one based on intellect rather than genetics, where the right to rule over others is determined by perceived intellectual superiority.'
To me, that's not racist. I do believe there are genetic dispositions amongst people of different backgrounds. For example, look at average height. If I go to Asia or South America and stand next to people I meet there, I would tend to be taller. Do I think I'm a better person than them because I'm taller? Fuck no. Can you appreciate this point of view?