I'm actually not sure if they did lie to Hawaii authorities - that is unclear. You can fill out the Safe Travels stuff 72h before, and you're good. You can get a positive test in the mean time. I'm also not sure they lied to UA - I doubt there's even an opportunity to do so. Do they ask at Check-In... Online? What if you get your positive at T-20 and you've checked in at T-24.
The other interesting issue is the Hawaii charge of "reckless endangering" - I don't see what that has to do with the State of Hawaii. The incident occurred in federal airspace, not within the jurisdiction of Hawaii, at all. In fact, their only actions within the jurisdiction of Hawaii was to walk from a plane to the checker folk, and drive home.
I'm not giving sympathy, but I feel they were effectively "trapped". Go home; where they have resources, and healthcare etc - or be stuck sleeping in an airport in San Francisco for a month.