I talked to Jim Ward about this at a convention once...he said the Arneson notes were mostly illegible drivel. I don't care how creative you are, if you cannot communicate your ideas to anyone else, it's irrelevant what you're doing. To discount Gygax because he didn't actually come up with the initial idea is dumb.
So, this is just old news...Arneson came up with a cool new idea, Gygax put it into a presentable form. I mean, they're both listed as co-creators of D&D, so who the fuck cares? Kuntz is just old and probably has a bone to pick with Gygax's widow who is the one tarnishing his legacy.
I don't think Kuntz has any real bones to pick with Gail--why would he trash Gary himself it that was the case? He did have a falling out with Gary in the last stages of the latter's life. I do sense some bitterness in Kuntz since he implies he's not interviewed much, and he's also apparently planning to write a tell-all book called Lake Geneva Days, etc.
The other thing odd was Kuntz stating the myth of Gary...but there's been a ton of coverage of the others involved with the creation. It's not the 1980s anymore, most people know it, both creators get credits in the OGL and in the books, even if it's small.
The thing people need to remember is this--Gary will always be better known. He didn't just co-create D&D, he developed all sorts of things. The Advanced ruleset. Tomb of Horrors, GDQ series, the World of Greyhawk, Homlett. Dozens of columns in Dragon magazine. He organized GenCon. He built a company, and he sacrificed his day job to do it. He was also naturally charismatic with people and spent a lot of his later years just chatting with folks online and answering their questions.
People know Gary better because he did more to influence the game in its early days and there are enough people who were inspired by all of that.