Nope, I am restricted from marrying my brother, but not because of my sexual orientation. He only wants the special treatment reserved for homosexuals, otherwise, it would cease to be special treatment.
USSC on classifications under the Equal Protection Clause... from GULF, C. & S. F. R. CO. v. ELLIS, 165 U.S. 150 (1897) – section used as precedent in McLAUGHLIN v. FLORIDA, 379 U.S. 184 (1964) which, in turn was used as precedent in Loving v. Virginia.
"But it is said that it is not within the scope of the fourteenth amendment to withhold from states the power of classification, and that, if the law deals alike with all of a certain class, it is not obnoxious to the charge of a denial of equal protection. While, as a general proposition, this is undeniably true, yet it is equally true that such classification cannot be made arbitrarily. The state may not say that all white men shall be subjected to the payment of the attorney's fees of parties successfully suing them, and all black men not. It may not say that all men beyond a certain age shall be alone thus subjected, or all men possessed of a certain wealth. These are distinctions which do not furnish any proper basis for the attempted classification. That must always rest upon some difference which bears a reasonable and just relation to the act in respect to which the classification is proposed, and can never be made arbitrarily, and without any such basis."
The fact that homosexuals are still allowed to marry those of the opposite sex does not make the bans constitutional in light of the Equal Protection Clause
This argument was put forth in support of anti-miscegenation laws and didn't fly because, as was expressed in Perez v. Sharp:
http://www.multiracial.com/government/perez-v-sharp.html
"...the right to marry is the right to join in marriage with the person of one's choice..."
While this case dealt with race, it doesn't change the fact that the right to marry is the right to join in marriage with the person of one's choice. Any restriction on that choice is subject to challenge and review based on the fact that marriage is recognized as a fundamental right. So, the fundamental right to marry is the right to marry the person of one's choice. This does not automatically make any restriction on the choice of who we marry unconstitutional, but the government must prove – and the burden of proof is on the government – that the restriction is not arbitrary and that it is necessary in order to further some purpose.
So, your argument that homosexuals still have the right to marry a person of the opposite sex – and, therefore, there is no invidious discrimination – is absurd. We have the right to marry the person of our choice and the government may only restrict that choice if it serves a valid State interest and the restriction is necessary in order to further that interest.