@BrodieOnLinux you DO control your comment section and other forums you can moderate, though. You DO have influence over your fans. They trust you, they listen to you. Whether you recognize it or not, you have power here.
So use it. Make a simple statement to your fans to stop harassing him. Let them know that abusing and brigading open source projects isn't fine, and you won't tolerate it in your community. Remove abusive comments and personalized statements about the developer.
Bare minimum.