You obviously didn't read to the end of my little post, yet feel righteous enough to throw that out…
> One allows the root user to create a kernel thread and then block its shutdown for several minutes.
Which as part of a compromise chain could cause a DoS issue that might be able to bypass common protections like cgroup imposed limits.
Depending on how much performance would be gained by using io_uring in a particular case, and how many layers of protection exist around your server, it might be a risk worth taking.