Informal/conversational English

Just received this text from a colleague of mine (he didn't give me the source). Would you say that the writer is claiming that informal/conversational English is incorrect use?

"Swan is a strong descriptivist who often classifies things differently from more prescriptive grammarians. What swan calls correct, I would call informal/conversational. What he calls excessively formal, I would call standard and correct."

She's/He's referring Michael Swan, I presume.

The use of the term "conversational" alongside the term "informal" seems to imply that the writer does not view such as "incorrect" across the board, but rather the writer is seeing from a literary standpoint, and is viewing such things as not "correct" usage *in literary contexts*. On the other hand, I would likely bet that Swan is viewing things from a spoken language-oriented point of view, which would be rather typical of most descriptivists, being linguists, for starters, and of course many things that may still be typically seen in writing would likely come off as excessively formal in most speech, even most formal speech.

On the other hand, I would likely bet that Swan is viewing things from a spoken language-oriented point of view,>

No, not particularly.