Is "in no way" informal?

Once in an undergraduate course on English academic writing, I wrote something like "This is in no way representative of ..." in an assignment, and the teacher marked it down for being non-academic.

I asked the teacher if the problem with the sentence was that it sounded hyperbolic or something and he reiterated that the problem was simply that the construction is not suited for academic writing.

To my knowledge "in no way" is equivalent to "not in any way" and is perfectly acceptable in formal, including academic, writing, unlike the simple "no way", as in "No way I'd do that," which, again to my knowledge, is informal.

Was the teacher wrong? Or am I? This has bugged me for some time.

"No way" has a long tradition of formality that is recognised as being distinct from current "street talk".

The skull shows good development and is in no way artificially deformed from Skeletal Remains Suggesting Or Attributed to Early Man in North America. By Aleš Hrdlička (1907)

That was in no way connected with your duty as prosecuting attorney? Answer. No, sir; not in any way whatever. from United States Congressional serial set, Issue 1489 (1872)

If GK Chesterton can do it, you can do it.

Yet at the time of Dickens's birth and childhood this weakness in their worldly destiny was in no way apparent; especially it was not apparent to the little Charles himself. He was born and grew up in a paradise of small prosperity. He fell into the family, so to speak, during one of its comfortable periods, and he never in those early days thought of himself as anything but as a comfortable middle-class child, the son of a comfortable middle-class man.

Charles Dickens GK Chesterton (1906)

Google Books edition