Seems like the normal usage to me. The post above lists other criteria that have to be satisfied, beyond just being a Rust implementation. That would be the consideration.
> To address this concern, the team at Google has agreed to apply their subject matter expertise to build a safe, performant, compact, and compatible JPEG-XL decoder in Rust, and integrate this decoder into Firefox. If they successfully contribute an implementation that satisfies these properties and meets our normal production requirements, we would ship it.
That is a perfectly clear position.
Seems to be under very active development.