That's how things get done. People get credibility by standing up, leading, and getting things done in the way Atwood does. He didn't have the "credibility" to partner with Joel Spolsky and create Stack Overflow either but I'm glad Joel didn't see it that way.
"Say, so-and-so, you wrote a really nice book but there are several errors in the first edition. We think it's great and we love it, and we see the potential in your work, so we're going to rewrite a second edition by committee then sell it under your title and byline without your permission; that cool with you?"
To my way of thinking, Gruber comes out of this looking churlish and unhelpful at best.
The more pertinent question is why Jeff didn't make more effort to base this off one of the existing standardisation efforts.