I'd say it's because LGBT rights are seen by conservatives as generally coming with more freedom in society and that correlates with higher child-bearing age, f

I'd say it's because LGBT rights are seen by conservatives as generally coming with more freedom in society and that correlates with higher child-bearing age, fewer children being born in general, higher abortion rates, and more promiscuous society. Not my views, what I see as the reasons traditional conservatives want to keep LGBT acceptance to a minimum.