The article says that the author wanted to hire someone who knows both Rust and C to maintain his company's embedded projects, but was unwilling to hire a C dev

The article says that the author wanted to hire someone who knows both Rust and C to maintain his company's embedded projects, but was unwilling to hire a C developer and wait for them to learn Rust. I'm not sure how this supports your point. I would argue that it's more that most companies aren't willing to let their employees spend a significant amount of time learning new skills.