On the most charitable level, the "huge math error" occurred in the calculation of the FDA's limits on exposure, so if the group feels that the FDA set its limits too high and the amount of chemicals being leached is worrying, then the math error really doesn't affect their conclusion at all.
But digging into the study, it becomes clear that the authors are really reaching in their methodology--subjecting utensils to rather implausible scenarios (when was the last time you microwaved your sushi tray?)--to try to get some samples that would exceed the limit. The hyperbolic media coverage of "ditch all your black plastics" isn't really sustained when the research finds that just a few specimens, when subjected to unusually high heat stresses, managed to just barely cross the incorrectly-calculated FDA threshold (itself likely set at a factor of a tenth to a hundredth of the lowest threshold observed to cause issues in previous studies!). That the authors aren't willing to disavow that media coverage is more telling then their unwillingness to adjust their conclusions in response to their math error.
> subjecting utensils to rather implausible scenarios (when was the last time you microwaved your sushi tray?)
That's not implausible. Sushi actually tastes better a little warm than chilled.
Also I think it would make sense to test all food trays the same way, as some of those do get heated quite a bit (e.g. I've microwaved take-out noodles in plastic trays very similar to a take-out sushi trays). It's not like it's plausible that there's some special sushi-tray supply chain where they've carefully determined they can safely get away with using e-waste plastic. It's almost certain that industry consists of many takeout tray companies that each make a whole line of takeout trays for different uses using the same raw materials (e.g. the sushi cart at my employer sold sushi and hot noodle soup in black plastic trays, which plausibly could come form the same manufacturer).
In general with all the microplastics floating around, I found it not a large investment to divest of 95% of the plastic in my kitchen (there was a lot), including the black variety, and only cook in stainless/carbon steel, ceramic enameled cookware, and glass with wood or stainless steel utensils and only drink filtered water. It's not hard to get most of the plastic out of your kitchen at least, but there are tons of other sources; clothes, furniture, devices, etc. I'm working on minimizing some of that as well. One of the most frustrating things is you can't find a drip coffee maker with an all metal full path for the water to grounds path. Everything I looked at had a ton of plastic unless it was $700+, so I live with the ritual of the french press for now
But digging into the study, it becomes clear that the authors are really reaching in their methodology--subjecting utensils to rather implausible scenarios (when was the last time you microwaved your sushi tray?)--to try to get some samples that would exceed the limit. The hyperbolic media coverage of "ditch all your black plastics" isn't really sustained when the research finds that just a few specimens, when subjected to unusually high heat stresses, managed to just barely cross the incorrectly-calculated FDA threshold (itself likely set at a factor of a tenth to a hundredth of the lowest threshold observed to cause issues in previous studies!). That the authors aren't willing to disavow that media coverage is more telling then their unwillingness to adjust their conclusions in response to their math error.