No, some container went rogue, and in the process dragged the Docker daemon which annoyed him PLUS he'd learnt that it was possible to run containers rootless and daemonless SO he changed his setup. Please RTFA.
Not the default hence not well tested. AND you still have a Docker daemon running. Furthermore, last time I checked, Docker does not support user namespacing in a released version yet.
I maintain the "duh fix your script dummy" is not the right attitude. The author clearly states it's used for a build farm. That is bound to fail ...
I read "Docker daemon was using 100% CPU" to be the recurring incident; not a given script. And when that happens, it ends up cascading and stuff get OOM-killed before you know it.
https://github.com/moby/moby/blob/master/docs/rootless.md
https://news.ycombinator.com/item?id=20542915