I agree with you that there are problems with the "born this way" argument. I can see where it comes from, though. In UK legislation there are what are called "protected characteristics", i.e. things on which it is illegal to discriminate, i.e. illegal to select candidates for a job according to those characteristics or to decide whether to serve a customer based on those characteristics etc. Things on the list include skin colour, and being male or female, i.e. things that are usually thought of as unchangeable, and not a choice of the person concerned. So the reasoning is, if sexual orientation can be established to be an innate trait rather than a choice, that can join the list of characteristics on which it is illegal to discriminate.
But, what if I could prove that being a serial killer is a result of the way the brain developers as a foetus and is thus already fixed at birth; that the serial killer cannot help himself and is only fulfilling his destiny? I can't see many people arguing that the loss of life is a reasonable accommodation to his nature. We would lock him up or, in some places, execute him just the same.
To me, its more a case that we don't have to have a narrow society in which everyone is expected to fit into a straitjacket. Does Tim Cook being gay have any bearing on the quality of the iPhone as a product? Of course not, only a bigot would think that. Does it matter if the headteacher of my daughters school is a lesbian? Of course not, if she leads the school we and, as a consequence, by daughter gets a great education then that's all I am worried about. Does it matter that a very bright electronics engineer who retired from my workplace a few years back came to work each day in a dress? Not if you have an open mind, it doesn't.
I get the impression that there are some in the USA who are keen to narrow people's minds again and wind the clock back to a certain extent and I can see why that would cause some anxiety, but I don't see how that bears on who does and does not appear in porn.