Rust has a semantic overhead and isn't quite as mature as Go. Their requirements don't necessitate a lack of GC pause.
You're right about maturity though. Hopefully the Rust library ecosystem continues to make strides.
To tie it back to the article a bit, Rust also seems like a relatively natural choice for a team considering switching from Haskell if their reason for switching is performance. The niche Rust fills for me personally is that it has a very robust type system (putting it in a similar camp as Haskell) with an explicit focus on fast, performant code (which Haskell does not have).