This isn't about Jim Crow style segregation. Nor is it about being "race" based (contrary to the article's vocabulary). The Kingdom of Hawaii and after the monarchy's overthrow the Republic of Hawaii were internationally recognized sovereignties. Before annexation, there were properly established diplomatic (British, French, Dutch, et al.) embassies in Honolulu. Further, Hawaii had fully functioning "European" style legislative and judicial systems.
The legality of Hawaii's annexation is a matter of debate. Though, such debate in reality lies in the philosophical sphere. As, it would be a matter of un-ringing a bell.
So, what is being proposed is something closer to the system in Quebec. There are recognized presumptive heirs to the throne.
The problem lies in the mentality of the sovereignty proponents. Are they willing to abide by the wishes of their monarch or do they want to return to the pre-Kamamah days before the unification of the kingdom.