They use zig to compile go code transpiled to C is what I got out of it.
Not really sure why they don’t throw some money at go so it could pin the glibc version it compiles against as that seems to be the stated problem.
I certainly would love to see this become equally easy in other languages / with standard toolchains. I write a lot of Rust. I have one program in particular that I'd like to make a one-binary install that works on old glibc versions. My program uses glibc both through Rust's std and through a C library (SQLite) it compiles/links in. I'd prefer to just throw a glibc version in my Cargo.toml and have cross compiling Just Work, rather building within a Docker container with an old glibc version, or having to install both Rust and Zig toolchains, or the like.
As to whether that's enough to justify for making a fuss about it, it's up to you, but you can't do that analysis if you stop at the title.
On top of all of that, the blog post and talk are about the journey that the author went trough to bring an unproven technology into their company and I think it deserves to be appreciated in a more nuanced way than a logo on a web page.