Probably originally written as a response against C++, Java or C# yes. However it’s also been kept up to date because it mentions Swift, so I think they don’t want to rewrite it in Rust or Go. But I agree that Rust might have been a good fit if SQLite had been created today. There is the point that sibling commenter made about small embedded systems though. But some people work on making Rust useful even for microcontrollers so who knows maybe a SQLite in Rust could have been highly portable too?