The blog post was drafted by the core and foundation team, however we did get sign-off from Mozilla on it.
Mozilla currently owns the trademarks that the Rust foundation plans to take ownership of, so they have to be involved to some extent. They have agreed to transfer it as mentioned in the blog post, and are going to work with us to make that happen.
The Rust project as an open source project with open governance has been pretty independent of Mozilla for quite a while now. However, Mozilla did provide some crucial services including trademark ownership, which is _extremely_ relevant to the discussion of forming a foundation.
Trademark ownership and is rarely impactful to the day-to-day workings of the Rust project, which is why I consider these irrelevant to whether or not Rust is still being "incubated" by Mozilla.
To be clear, I don't have any real concerns here, it just seemed a bit inconsistent; the foundation sounds like an important new phase, and I am a very happy Rust user who is somewhat amazed at the extent to which I have come to feel that I can not only use it in places where a compiled language obviously makes sense but that it is convenient enough that I could actually replace some of my prior usage of dynamically typed/interpreted languages.