There were a couple of things I learned in linguistics class that turned out to be wrong, but at the moment I only recall one: they told us that no native English speaking child would ever say "What did you eat eggs and?" because this construction doesn't occur in any language. Nevertheless, I heard my nephew, who is Guyanese (an English speaking country) say this very sentence. What led whoever this textbook was quoting to incorrectly conclude this, especially so broadly?
There is a long-standing theory in syntax to the effect that no language could do this (the coordinate structure constraint, or similar ideas). It's not as well known that the underlying claim is actually not true. One excuse is that there has been equivocation over what constitutes a "conjunction". Many Bantu languages violate the constraint, except that the "conjunction" na is also the word "with" (the limit is not about "everything that could be translated into English as 'and'").
You could pursue the author(s) of the textbook and inform him/her that the underlying linguistic claim is discredited. The author might, reasonably, ask for your evidence that the child did in fact say this (reporting errors in child language studies abound). You might instead focus on the question of whether the author should know of the problems with the claim.