Docker didn't have much of a choice. At the time they had two options: C/C++ or Go (Rust wasn't usable at). They went with the right choice at the time, Go. Unfortunately nobody really knew about all of the pitfalls of Go (there are many upsides, but writing a container runtime in Go is definitely not one of them).

Right now, I would definitely recommend people write things like this in Rust. In fact I was planning on working on something similar. :P

Author here. As I mentioned in another comment. I should have clarified that its shortcomings are specific to the container runtime (i.e. the part that creates and enters the namespaces). Go is a great choice for the command line utilities and daemons. I am a big fan of go in general, and even the container builder smith is written in go.

Don't generalize from this post. That's a trap. Go's runtime model doesn't interact well with stateful namespace syscalls in the Linux kernel, and it's hard to fix. That's all that can be concluded.