No it's not. Marriage is clearly defined in law as being between man and woman. All this statute does is try to penalize a certain group of people for not harming anyone else.
If homosexuals were required to state on their health insurance forms their sexual preference, do you think they would be able to afford the premiums that actuaries would set for them, given all the health problems that come part and parcel with homosexuality? Of course not.
The broader heterosexual community is subsidizing the gay lifestyle. They can't survive without heterosexuals. Thus, if I'm paying for it, I can regulate it.