They can't "go to any lengths" to find out about a program that they don't know even exists.
The billboard does not reach out and grab people and force them to sign up for these programs. Just viewing a billboard will provide the inspiration for someone who truly wants to change to seek out the program. Not knowing that these programs exist and being constantly told that change is impossible may drive these people to despair.
You are indeed out of control if you feel threatened by a billboard.
There is not a gay person alive who doesn't know there are programs stating they will help you change if you want to. A billboard will attract nothing but negative attention. That being said, it would be like Jews for Jesus for me...I don't care if a billboard is up for that, although I think the organization is ridiculous...but do you reallly think it's going to change the life of an unhappy Jew driving by and seeing it?