Microsoft, Apple, Amazon, Oxide, Mozilla, Dropbox and CloudFlare would like a word...
I'm aware of at least two ongoing projects they're writing in Rust, which I obviously won't comment on in detail publicly.
Tier 2 means it requires approval. That is massively different from "forbidden". There is, for example, a Tier 3 list - Java is on there, some other languages, they're discouraged a lot more strongly than Rust though you'll still find them in some parts of the codebase (primarily acquired code from what I recall). Approval is only required for business/ product dev - non product teams can very easily write rust, at least one is currently doing so.
Tier 2 means it has internal library support, such as the communication library. That means there is, at all times, active rust development - and of course this is true, the most critical parts of Dropbox are written in Rust, and they rely on those libraries.
You can also very easily find out about the existing projects being written in Rust. Go ask the rust-lang channel. Last I saw, maybe 6 months ago, Rust was being used for another major component of the product - obviously I'm not commenting publicly on that further.
It is definitely not the case that any randomly selected backend engineer at that company can just pick up Rust and solve any problem with it, because the Tier 2 status is used as a cudgel to stop most such efforts.
I agree with your point about political issues - the entire tier list, specifically even Rust being tier 2, was political. I saw stupid shit like that too many times at Dropbox.
But it is simply a fact that new projects are being built in Rust, regardless of the political aspects of why that is the case despite it being tier 2. "Forbidden" does not convey the state of things - everything else you've said is agreeable.