They claim they got the IRB to say it's IRB-exempt.
https://www.startribune.com/markingson-case-university-of-mi...
The way I've seen Harvard, Stanford, and a few other university researchers dodge IRB review is by doing research in "private" time in collaboration with a private entity.
There is no effective oversight over IRBs, so they really range quite a bit. Some are really stringent and some allow anything.