People do that because there are "Christians" who openly advocate violence against gay people, and if you have any grasp of history, it is easy to see where fundamentalist religions take these kinds of issues.  Just as it's easy to see where most extremist/reactionary movements go. 

Plus, Jerry's been promoting hate in this city on this topic for a long time.  He more or less built his little Baxter Road empire on anti-gay bigotry and it works for him.  If Christians don't want him to be their spokesman, they should speak up and drown him out.