(Link worked for me ...)
This “Tier-1 language” engineering status for Rust means giving internal teams a paved path from local development to production: secure toolchain builds, productive developer tooling, quality workflows, deep platform integration, and compliance with the SDL requirements Microsoft software must meet.
Specifically, it joins a list of existing Tier 1 languages (C++, C#, and TypeScript), as "one of the best-supported languages for internal development at Microsoft"
Java and Python are not on that list?
Microsoft explicitly de-emphasized Java in favor of C# after their J++ lawsuit. That's why they created C# in fact.
Python for windows application development never really got there and is kind of a technically runs if you want to run python kind of situation.