New Logical Fallacy: Argumentum ad Grammarnazium

Argumentum ad grammarnazium: Bringing up a perceived error in grammar or spelling as proof that the opponent is too stupid to be believed, with bonus points for:

• confusing style with grammar and thus "correcting grammar" that was already correct
• correcting an appropriately employed colloquialism
• insisting that the Oxford comma is wrong and should not be used*, **.

Example: correcting the possessive form of the name Keks from Keks' to Keks's, on the grounds that Keks' is not a proper possessive. (Keks' is AP Style and Keks's is MLA Style.) Point conceded due to MLA style being more appropriate to the circumstances even though neither was on point.

Example: correcting the spelling of "offences" to "offenses" in an article written by someone in England about a new policy in the UK, effectively correcting the British spelling with the American spelling, while feigning incredulity on other claims made by the same author.

* The Oxford Comma is the application of grammatical parallelism to comma usage.
** OK, maybe I am a grammar nerd.