You usually can't get divorced in any state but your state of residence. (you can typically get married anywhere)
So he probably can't go to HI to get divorced.
Why am I not surprised this was Maricopa County?
That said, I'm not surprised with the ruling. Other states have said either chromosomes matter (FL, TX, OK) or genitals matter (NJ). I don't know of any ruling in the USA that says someone with female anatomy can marry a female woman and not have it treated as a same sex marriage. DOMA also allows a state to not recognize a "same sex" union, but doesn't require a uniform definition of "man" or "woman". So a legal heterosexual marriage in one state may be an illegal gay marriage in another, under the law.
Add to that, people think that because the courthouse will give you a marriage license after you show a Driver's License or ID card, people think that this is proof that your marriage is a legal heterosexual one. It doesn't work that way - it is based on the reality that the documents describe, not the documents themselves, even though they won't make you prove that the documents describe accurately what the state really considers important to determine if someone is a man or a woman. So a state without legal gay marriage but uses the chromosome standard, for instance, won't care if you showed someone a birth certificate or driver's license - your marriage will be invalid if you have the same chromosomes as your spouse. You might get a marriage license, but it's not legal - it's void and the state sees it as fraud.
It is why any heterosexual trans person who doesn't support same sex marriage is hurting themselves. You might not be gay, but that doesn't mean the state doesn't think you are.