proof of a negative test is pointless - it is only good for the moment the sample was taken. After that, all bets are off because the person could be infected an hour later by some asymptomatic person walking around the airport spewing virus all over the place (a la the USS Roosevelt and everywhere else around the planet).
In addition, there are periods when a person has the virus but tests negative. And most of the tests right now have unacceptable rates of both false negatives and false positives (I wonder, what's an acceptable rate of false results?) like the ones in use at 1600 Pennsylvania Avenue.
If I get rejected from travel for a false positive, who is gonna pay for all my expenses - the state of Hawaii? WN? travel Insurance companies? And, as mentioned earlier, what if only one person in the traveling party tests positive? "No, no, no, that's okay honey, you and the kids go on without me...I will be fine hanging out here at SFO until you get back...."