He made the decision to take it out of the collection and stop printing it. It was indirectly linked to a few school shootings, and he didn't want it on his conscience. It's basically a story where the school shooter is sort of the good guy and all his classmates come to respect him after he murders some adults, so I can see why King would choose to let it go, even if it's not actually his fault if anyone is already unhinged enough to take inspiration from that.