Universal had a mitigation plan for HHN, including plexiglass in the houses. From my understanding, the county APPROVED HHN but did not WANT HHN to go forward (there’s a difference).
It was a combination of the county’s lack of support, Netflix pulling out, and the other IP holders having concerns about the event (and their likely withdrawal once the first domino fell) that led to HHN’s cancellation. All signs were pointing to Universal being on an absolute island if HHN became a super-spreader event. They objectively checked all the boxes, but that doesn’t mean they were supposed to.