Every person with a larger online following is absolutely partly responsible to their fans behavior when it happens en masse. Especially if your audience is partly kids. They look up to you and you profit from them consuming your content so it’s your moral responsibility to direct them in the right direction.

That’s why I’m asking if he put out a message strongly discouraging this behavior. And, no, ultimately, you have no control of what those fans do in your name. Your responsibility ends if you make a good faith effort to call those fans out for and show strongly that you are not supporting their behavior