This brief post by Matthew Schmitz in First Things discusses Ayn Rand's comments on C. S. Lewis's The Abolition of Man.
I highly recommend Michael Prescott's post The Importance of Being Earnest which is a detailed critique of Rand's comments. Most importantly, he points out that Robert "Rewrite" Mayhew's editing is suspect.
The synopses of The Abolition of Man provided by Marginalia's
editor Robert Mayhew are sometimes inaccurate. For example, with a few
words in square brackets Mayhew summarizes part of Lewis's argument in a
quoted passage: "[Those who reject tradition] are not men at all: they
are artefacts." But Mayhew has conflated two different sentences, which
have two different subjects. The actual passage reads: "It is not that
they [i.e., the Conditioners] are bad men. They are not men at all.
Stepping outside the Tao, they have stepped into the void. Nor
are their subjects necessarily unhappy men. They are not men at all:
they are artefacts."
Thus, while "they are not men at all" does refer to the Conditioners
(whom Mayhew somewhat inadequately labels "those who reject tradition"),
the words "they are artefacts" refer to the Conditioners' helpless
victims, who have been remade (via eugenics, prenatal conditioning,
education and propaganda) into something no longer human.
Perhaps such inaccuracies are explained by a comment Mayhew makes in
his introduction. A true acolyte, he unabashedly praises Rand, writing,
"I do not recall a single case [in her marginalia] where what she said
was unfair." It's good to know that when Rand railed against Lewis as a
bastard, monster, scum, etc., she wasn't being unfair. Mayhew continues,
"In fact, I was often filled with admiration for her patience, and for
the strength of her stomach, in being able to go through some truly
horrible book that she had decided was worth reading. (I, for one, could
never have completed C.S. Lewis's The Abolition of Man.)"
I suppose if Mayhew wasn't actually able to read Lewis's book, he would have been hard-pressed to summarize it accurately.