Even 100k LOC is pretty small for a software project, and likely doesn't need more than a few engineers. The advantage of the simplicity of Go shows up when you have to coordinate across >100 people, many of which are kind of mediocre, and you need all of them to ship features. If everyone in the world were a genius who is obsessed with writing clean code, Rust would be a fantastic language to work in at that scale, but they are not.