There is a numbersnumber of claims, which rise to the level of an urban legend, that Texas has a historical right to secede. As the linked answer shows, it does not. But the persistence of such claims makes the question about Hawaii different.
Answering the question about Hawaii does not involve debunking false historical claims. In other words, it allows considering this (obviously hypothetical) question in isolation from the other questions (present in the case of Texas).
The only possible reason I can see for closing it would be that it invites speculation since there is no established law on the topic.