Merrill's critique only concerns the style and manner of Rand's writing
For example, 'Rand mentions Kant repeatedly (he seems to be the guy she loves to hate), but there is absolutely nothing that is specific. She never quotes Kant directly, but when she apparently feels a need to justify her view of Kant she instead quotes from a book published in 1873 by Henry Mansel whom she describes as “a Kantian”. Again, I am not an expert on Kant, but who is this guy Mansel? I can find him mentioned in none of the histories of philosophy I have, and he is not mentioned in the fairly extensive bibliography on Kant in Lewis Beck’s 18th-Century Philosophy. So direct reference to Kant is replaced by reference to “a Kantian” (and a very obscure one at that). Why do this? Why not show how Kant himself held the position that is being attacked? There is no justification for this sort of thing. Again, poor scholarship. (I do not, by the way, believe that even the quote from Mansel supports Rand’s view of Kant. But I will not argue that point now.)'
I am at present reading the Mansel book quoted by Rand. If Mansel was a Kantian, he was only 2/3 Kantian at best. Did Rand know about neo-Kantianism? At least Mansel has the distinction of reading the Critique of Pure Reason, and in the original German. Rand had never distinguished herself in that way, either with the German original or any English translation.
Mansel trashed Kant's literary style. And yet, he excused it as a natural product of the German language which delights itself in never-ending sentences and multi-syllabic expressions. Mansel seemed to approve of the Aesthetic and Analytic sections of the Critique, but utterly opposed the Dialectic of Pure Reason. He held that this section had led to the numerous metaphysical errors that future German philosophers were guilty of.
Upon reading these key sections of Mansel's book, I can only conclude that Rand "borrowed" many of her future ideas from Henry Mansel's Letters, Lectures, and Reviews.