I honestly don't see the problem. If a gay person thinks that conversion therapy will cure him and chooses to go through it, then it is his choice. Nobody is forcing anyone to go through it.
@applejack It doesn't have to be religious. I bet some might think the would live a happier and/or healthier life if they were heterosexual. Granted, they could just not have gay sex, but maybe they want to remove any temptation. However, I don't know if any of these therapies actually work. LGBT rights advocates say they don't, but that's just them.
@xianc78 I suppose so
Best explanation for homosexuality is the genetically antagonistic theory, which would mean it is fixed
https://slate.com/technology/2008/06/a-genetic-theory-of-homosexuality.html