That great work is mostly opaque on the outside.
What's been noticeable as an observer is that a lot of the well known names associated with rust no longer work on it and there's been a large amount of turnover around it.
That manifests in things like this case where work was in progress up until ~2021 and then was ultimately backburnered while the entire org was reshuffled. (I'd note the dates on the MCP as Feb 2024).
I can't tell exactly how much work or what direction it went in from 2021 to 2024 but it does look apparent that the work ultimately got shifted between multiple individuals.
I hope rust is in a better spot. But I also don't think I was being unfair in pointing out how much momentum got wrecked when Mozilla pulled support.