Jeff Atwood is a blowhard sure, but you're ignoring the history here. Gruber has refused for years to acknowledge that there are any problems with Markdown at all. Some argue that he has the right to do with his creation as he wishes, but that misses the larger point that Markdown has communal value far outstripping Gruber's original contribution of aggregating a bunch of ascii typographical conventions and compiling them in the spirit of Textile.
By sitting on his high horse and proclaiming Markdown "works for him" and that his unspecified version with tons of nasty edge cases is canonical and that not only is it correct, he won't weigh in on any formal specification, he deserves to be case aside and have the project taken forward without him. He doesn't have a moral claim on something as simple and widespread as Markdown, and the fact that he finally has to deal with someone with similar blog reach going on a crusade is nothing worse than he deserves for sticking his head in the sand.
By sitting on his high horse and proclaiming Markdown "works for him" and that his unspecified version with tons of nasty edge cases is canonical and that not only is it correct, he won't weigh in on any formal specification, he deserves to be case aside and have the project taken forward without him. He doesn't have a moral claim on something as simple and widespread as Markdown, and the fact that he finally has to deal with someone with similar blog reach going on a crusade is nothing worse than he deserves for sticking his head in the sand.