Sorry if this is beyond the statute of limitations for a reply, but tapa isn't good at notifying posters when you're mentioned or have a dm...
This is the slide that produced the original story:
link: MI COVID response Data and modeling update (michigan.gov)
What I'm still unclear on is their methodology. Based on the footnote in the lower left, it seems as though they're counting cases from the 5-18 age group and then applying it to the public school area that those cases are originating in. So, in ATX terms, if a 10 year old in zip code 78758 gets sick, they'd see that as a case for a school with "masks required" even if that kid went to private school with a lax mask policy or was home schooled.
So the article was printed based on that slide.
Michigan then continued the study, as it's relatively easy to do once you have the dataset set up. Through 12/6 here is the same slide.
link: MI COVID response Data and modeling update (michigan.gov)
And this was presented really before Omicron took off. I'd suspect they'll update it again in the near future and the lines will still overlap.
The second graph doesn't mean masks don't work, just like the first graph doesn't mean that masks do work. The study was flawed in their data collection.
After doing some digging on why they weren't pulling data directly from school district data, I found my answer when I ran across this article:
How many COVID cases are in Michigan schools? State has no idea anymore | Bridge Michigan
Basically, if you really want to present an argument as gospel, there's a dataset out there that will support your claim (which is why we have crazies everywhere).