If we lived in a world where homosexuality was somehow "reversible" with diet and exercise, would you expect to see LGBT groups/support taken less seriously?
Unfortunately, yes. I would expect that from most people.
Just make heterosexuality reversible as well and you've got a deal.
Somewhat, it would be downgraded to a reversible condition comparable to obesity, not seen as something you have to live with. Those who even now claim it's a choice would not change their opinion of course.