I'm curious why a question like this is even asked. How in any way would his belief if it's a choice to be gay (which its obviously not) affect his ability to run the country. I wish we could actually talk about the issues for once.
Here is why. If you believe being gay is a choice, then gay people should be treated like model train enthusiasts. You have nothing against them and they have every right to enjoy their 'lifestyle' but they shouldn't have any 'special protections.' Whereas if you believe it isn't a choice, then sexual orientation becomes like race/ethnicity. And therefore deserves protection from discrimination.