It's an odd sort of "review" that mentions the notional subject mainly in passing, but no matter: his remarks on Heinlein are right to the point.
In particular, I like his emphasis on Heinlein's gift for effortless simplicity. Heinlein always reminds me - now don't laugh - of Joseph Haydn. Haydn was one of the few true greats. He invented many of the forms which would shape and dominate music for a century or more (including both the symphony and the string quartet), yet on face value his work seems remarkably simple. It's pleasant, very easy to listen to, and entertaining as well, but rarely takes your breath away with the spectacular showmanship of Mozart, Beethoven, or Bach. It is only on repeated listening that you gradually realise how much depth there is in it, and start to feel a bit foolish when you remember that at first you though it "simple". I don't think one can learn that sort of "simplicity". It's a gift.
Sound familiar?
Take Glory Road as an example. It is just a straightforward fantasy adventure simply told, and because the telling itself is so unobtrusive, the tale itself lives in a way that more "advanced" writing cannot emulate. Or consider Double Star where we see the same thing. Even when Heinlein decided to do something obviously different - I'm thinking of The Moon is a Harsh Mistress - his gift for economy remained effective.
Thanks for posting the link, it was a good read.