Your premise is faulty. The majority of focus is on homoexuals because they represent a small minority outside the norm.
Christians who wrongly interpret the Bible harp on it, and bring focus on it. Rabid homosexual activists who demand everyone think they way they want, or compromise their free exercise of religion, abandon their right to association, bring focus.
I don't even think about them, except theoretically here. Otherwise I go about my business. If someone wants to know what my faith says about them, I am happy to share. I do find ludicrous and hilarious the permutations that homosexual apologists go through in trying to reinterpret the Bible and Christian history to support homosexuality as being A OK in the faith.
"Sexual orientation" and "gender" are social and political terms driving the nebulous science of psychology bending to social pressures. These terms have little to do with biology or genetics. Is necrophilia a "sexual orientation" ? If so, does that mean it is socially acceptable ? If not, why not ? Would you be pals with a necrophiliac ? How about a pedophile, these folk meet your definition and contrary to popular opinion, in moslem society, by their rules, it is perfectly normal and not harmful. Would you argue that a 60 year old moslem with 11 and 10 year old wives had just a sexual orientation ? Are there any lines that "sexual orientation" cannot cross ? A woman loves her St. Bernard, he loves her, they have sex, she loves that, he loves it. Is that just her sexual orientation ?
Okay I would agree that gender and sexual orientation are rather political and social. But you have yet to answer my question. If being gay is a choice, when did you choose to be straight?
It's pretty straightforward. If one orientation is a choice, then it would stand to reason that all of them are. Otherwise you can't choose it to begin with!!
Pedophilia, Necrophilia, Bestiality etc are not recognized as sexual orientations. Rather sexual paraphilias (sp?) And they involve non consensual sexual activity. A child cannot legally consent to sex. A dog cannot consent as understood by our parameters, neither can corpses. So they are all inherently non consenting sex, ie rape.
Thus I can point out a very specific aspect that is found in all such scenarios and give an argument as to why it is not ethical.
Can't really do that with two consenting adults of the same sex, though.