The freezing is only because of parasites, not microbes. It doesn’t kill microbes. Practically all of the fish you purchase is actually sushi grade, having been flash frozen on the boat, it is a meaningless term. If you go to a restaurant, supply store, or a fish wholesaler, you will have a hard time finding any fish that is commonly consumed as sushi that isn’t labeled sushi grade. It’s like how nearly everything that doesn’t have wheat in it is labeled gluten-free, it isn’t because they did something special.

Her temperature charts show it getting well above 140°F, which is the temperature at which all of the parasites die, and they do not form spores or come back later. So it is completely safe in that regard also.