Forking is not as trivial as you make it sound. You need to setup CI/CD with the new fork, then persuade the community to get on board the new fork. The bigger problem is to get the infrastructure and money to host a live CDN that serves the users.
Even then, it's not even clear how trustworthy any forks are. And the risk of the project fragmenting becomes high. Which is the "real" CDNJS if the original becomes stale and two credible actors both decide to fork it at the same time? In reality, there will end up being links to all three projects.