No people that are politicizing it are trying to control the narrative of a tragedy. They are using fear to bypass people's reason and their values. It's exactly how you get someone like Trump elected president. We should listen to the victims and to the investigators we should not be using public fear to further arguments we were already making.
No it's because it's been stigmatized as immoral. Fate is not a good argument to show that there is nothing immoral about being LGBTQ. Being born a certain way has never stopped people from dehumanizing that group. In fact I would argue that it makes it easier. It makes those people defective, truly other than. It makes it easier for people to justify murder, sterilization, etc. There are plenty of very good arguments that are consistent with our values in a liberal democracy and that draw on our history that has steered toward more tolerance for both why it is not immoral to be LGBTQ and why people should accept them as fellows. Please do not water down our values to genetic fatalism. It is that thinking that started the eugenics movement and all the horrors of the 30's and 40's.
I really hate this argument. Attacking it from another angle, there are a whole host of really terrible things that we would have to accept as moral if we accept this argument. I will have no part of it. It just isn't immoral to be gay and it doesn't matter if someone chooses to be or was born that way.