Hawaii wasn't even a U.S. state in World War II (it was admitted to the Union in 1959), so as far as I'm concerned the people of Hawaii had no more obligation to "side with the USA" than the people of Japan did.
It's worth noting that a nation formed by "traitors" really has no credibility when applying that description to anyone else.
Your position is relativistic.
One can be a "traitor" against a bad regime, in which case it is not a vice. However, when one is a traitor against the greatest nation on earth, it is definitely a vice.
I find it hard to believe that you have not faulted Hawaiians for joining the Japanese.