I find my games (~1100 Elo) rarely make it to Mythic, so his idea of ranking them according to comeback potential really strikes me as a good way to judge Mythic godpowers. Basically, in 1v1s, going to Mythic is most often used either to finish off a game you already know you've won, or as a last-ditch effort to save an otherwise lost game. And it's that last use case where the relative powers are most important. (There are exceptions of course, like Survivalist's 90 minute epic from a couple of weeks ago.)
I had a game a day or two ago where this kinda seemed to be the case. I was pretty solidly winning, and it was getting close to the point where I was wondering why my opponent hadn't resigned yet, when he got up to Mythic (I was still in Heroic). Then he used Ragnarok. That made it instantly make sense why he'd hung on. Unfortunately he had already lost 2 TCs, including his starting TC, and was only surviving on one corner TC. And at the time he used Ragnarok, he only had about 60 food, so was completely incapable of rebooming behind it. So yeah, it didn't work. But worth hanging on to try it out.
What wasn't worthwhile was hanging on another 10+ minutes past that until his very last Gatherer...