It seems like part of the problem for his response has to do with citing T2D to begin with, and the fact that a lot of people here are familiar with T2D research. He didn't seem to ask for anything about "normal, healthy people" in the beginning (and we have to define those terms anyway), so research wasn't given on that.
On the other hand, there is a lot of research on that kind of group, or really on elite athletes. As I understand, that was the primary group Drs. Phinney and Volek were working with (particularly with endurance athletes) for much of their research (maybe they still do), and I believe that's also Tim Noakes main field. I believe they show the benefits for that group in their improved endurance performance (setting records for super-marathons, etc.).
Of course, it sounds like once you present their information, he might just say, "but you aren't a super endurance runner either".
The research otherwise may be out there for exactly what is sought, but I'll put things this way: the reason I started a nutritional ketogenic diet was that the research convinced me it was not likely to do any harm, at any rate, and it appeared to be the easiest and most enjoyable way to avoid things that research convinced me would do harm (sugar in the forms of sucrose and fructose specifically). It just appeared to be a practical choice, even if there were alternative methods (and indeed, I'm still open to the idea that alternative, drastically different methods are equally or even more effective, at least for certain populations).
On the vegan note though, when I looked into that research, they claimed nearly identical results, but had a hell of a lot more doubtful evidence and less convincing arguments in their favor. But, hey, maybe they work to certain degrees too? There does seem to be indications that the Standard American Diet at least is simply the worst route, and switching to nearly anything else is better.