Longer answer: It's hard to find programmers who can or are willing to write/maintain code in the style of the old GNU hackers. Starting afresh with modern development practices in Rust is more likely to result in a project that gets actually maintained over the long term after those old hackers die/retire/etc. Starting afresh also allows you to bring in more prosocial practices that are table stakes for modern OSS development but would be met with resistance from the GNU community, including using a permissive license and having and enforcing a Code of Conduct.