Framing Mozilla as the “steward of the language” is one reason why we’re making this move. Don’t get me wrong, Mozilla is important to Rust, but (in all things other than the trademark, which is a nuclear option they’ve given no indication of ever using) the relationship is much more of a “large supporter of” then “in control of” one. Having a foundation would make this much more clear to folks who aren’t deeply involved in Rust.