Oh I think he gets those ideas, but as can be gathered from his characters, he doesn't think people will go for it. And the spacers in 2312 are pretty transhumanist I'd say.

I have not read 2312 yet, although it is on my list. As for most of his other works, he explores ideas of immortality and such, but only in the context of humans. He explores what happens in a society where humans live forever, without all our weaknesses, idiosyncrasies, and quirks. He also presumes such biologically limited humans will remain the dominant species and their tribal power structures the mechanism effecting change. That makes for good storytelling when your audience is regular old humans. But not very accurate predictions.