No you're absolutely correct. His criticism of Freud anticipated Murray Gell-Mann, or rather his eponymous amnesia effect, by at least a generation.

It's been quite a few years so the exact phrasing escapes me now, but was something to the effect that Freud demonstrated a pattern of confidently talking well past his own level of understanding of certain topics even in the company of actual experts in the material, And thus although Lewis couldn't judge to what extent this was a factor in Freud's own claimed area of expertise, he observed that when Freud ventured to hold forth on something CS Lewis did know quite a lot about, namely, languages, he found him to be quite the amateur. Freud is somewhat obliquely caricatured thrpuhh the character of Sigismund, a personifcation of the more cargo cultish, callous and anti-humanist excesses of self-indulgent charlatanry marring the then-nascent psychotherapy movement as a whole.