> This misconstruction is very common, included in print publications spanning several centuries. It might be considered an alternative spelling, albeit still a mistaken usage.
Thanks though, I never actually knew so was helpful :)
Google Books search for the misspelling returns notwithstanding. A forced search for the misspelling shows nearly all of the errors are reprints of low quality lawsuit text, with one or two prose errors - not sure who is reading bad lawsuits in book form. Zero examples spell it as "non-with-standing".
The wiktionary definition reads like a student got bad marks and raced to add it to wiktionary to argue with their teacher. The only other "dictionary" with the definition is quoting this one. Even that drops the feeble "might be considered an alternative" claim. It isn't.