You are correct, the absence of choice does not make someone unaccountable.
The problem with your statement is that it was taken out of context. The only reason to argue that homosexuality is not a choice is because of the people that state it is immoral -because- it is a choice. So for them once we've established whether it's a choice or not, we can determine whether it is right/wrong to practice.
But in any case, it shouldn't matter whether homosexuality is a choice or not. Any action can be determined to be right/wrong by refering to the basis for human rights. Mainly, the right to life, liberty, and the persuit of happiness. The right to property should also be in there, but that's not important here. The point is, any action needs to be compared to these rights and whether or not they violate them.
A benign example - color preference. I like green. I choose to buy clothes that are green. This action in no way harms anyone else's right to life, etc.
Homosexuality - if two consenting adults would like to get together in the privacy of their own homes and do the bad thing, what does it matter to me what sex they are or what they do. My right to life, liberty, property, and the pursuit of happiness are unaffected.
Pedophilia - a person who molests/abuses a child is violating the rights of that child. Physical as well as psychological damage has been done to this child against its' will, therefore violating it's rights. Regardless of the motivation of the perpetrator (be it drugs, instinct, choice) it is against the law. The motivation will only determine the severity of the sentence (as far as I know).
When someone says that another persons' private action is violating their right to the pursuit of happiness, you must look deeper into their motivation. But regardless, if they pass a law against homosexuality - that violates the rights of the homosexuals, just as it would violate my rights if they banned the color green.
Also I would like to note the difference between "against the law", and "immoral". As it stands liking the color green and buying green items is not against the law. However, I might come from a culture in which green is a sign of the devil and thus liking/wearing green is considered immoral. Therefore I would never asscociate with the color green and would believe all those wearing green will go to hell, but it won't be against the law to wear green. Were I to get it made against the law to wear green, then the moral and the law would coincide.
Therefore, right now to say homosexuality is wrong is a moral stand, an expression of opinion. This person would choose not to associate with homosexuals. No one's rights are violated. Arguing wether homosexuality is good or bad is usually an exercise in futility - most people will be set in their ways. However, arguing wether homosexuality should be against the law is an entirely different animal. The law would need to hold up to the bill of rights.