I'd say definitely not irrational in March/April.
But, today is not March 1. Today we know much about transmission. We know symptoms. We have testing. We are aware of asymptomatic spread. We are wearing face coverings. We are socially distancing. And, Hawaii is almost, if not entirely, free of infection. Notably, even before ANY of those things, with unrestricted tourism, Hawaii handled it perhaps better than any other state in terms of deaths, cases, etc. They never ran out of beds or ventilators. They had the lowest per capita death rate in the United States and only Montana has fewer cases per capita. Hawaii defended against the virus DESPITE tens of thousands of tourists from across the world coming in during Jan, Feb, and March -- with NO mitigation measures in place, and a LOT of undiagnosed disease out there. So, basically, Hawaii won.
My point is, what was very rationale then may not be rational in July or August. At some point it is no longer rational. Fear is not a good policy driver. Perhaps if there were not a significant downside it might be. But at some point the economic injury to the PEOPLE that live and work there becomes irreparable.
To play a mind game, let's assume there are no more new cases in Hawaii during the remainder of May. And let's assume that continues into mid-June, almost 30 days from now. No cases. Under that hypothetical, would it THEN be irrational to say Hawaii needs to continue to have essentially sealed borders (the impact of 14-day quarantine) to tourists?
On the flip side, Hawaii could mandate hotels/timeshares could open to 30% capacity and require all visitors to certify that the got tested within 2 days of departure, and require that proof of a negative test be shown upon arrival. They can impose restrictions on dine-in locations and at other "high risk" locations. No big gatherings. They may get some active cases -- but 10 or 15 are manageable. The alternative is to wait until vaccination and require proof of vaccination before they open up. That's an economic disaster.