This "choice" stuff is such a red herring.
A pedophile doesn't "choose" to be attracted to children, but it's still illegal to have sex with children. A rapist doesn't "choose" to find rape gratifying, but rape is still illegal. A polygamist doesn't "choose" to want to have sex with multiple women, but bigamy is still illegal. People in incestuous relationships don't "choose" to be sexually attracted to close relatives, but incest is still illegal. Exhibitionists don't "choose" to be sexually excited by exposing themselves in public, but it's still illegal. Etc. Etc. Etc.
Basically nobody "chooses" what sexually excites them, but that has nothing to do with whether the conduct should be illegal or not. With the most obvious example -- child molesters -- there's lots of proof that they can't help themselves and there's a very high recidivism rate. That's completely irrelevant to whether the conduct should be illegal.
Anyway, whether there should be gay marriage or not, etc. has nothing to do with whether anyone "chooses" to be sexually excited by members of the same sex. What should or shouldn't be legal is an entirely separate question.
To get back on topic, Elton John is famous because he's a great performer and musician and a very good composer of pop music. None of which has anything to do with whether he is gay.