My only point is how many in the Rust community advocate as if Rust would be the first language having features, that actually were already in Ada for the past decades.
As for Ada on Linux, naturally Linus would never go along it.
A C kernel guy liking a language with Pascal syntax, a community that worships a paper that hasn't been true in the Pascal world since early 80's, not even at gunpoint.
If you want to see a use case where Ada was chosen against Rust, check NVidia's project for self driving vehicles firmware.
Plenty of safety conscious language have had followings since ALGOL, this is the point that many miss when praising Rust, while ignoring our computing history.
I think that is a false perception created by the dev-blogging community. Based on GitHub activity (https://madnight.github.io/githut/#/pull_requests/2021/2) Rust usage is declining (absolute numbers show little growth). Based on developer surveys (https://www.jetbrains.com/lp/devecosystem-2020/) very few people use rust outside of hobby development.
I think the concern is that the core argument that "I think Linux should adopt rust for safety" is a bit dishonest, given that there are a large number of well-vetted alternatives. "I think Linux should adopt rust because I like rust for social reasons" would probably be more correct. That Google staff seem to think rust is good for the Linux kernel but not, say, Zircon, would be surprising if those same people actually believed that any legal rust program is safe and inherently trustworthy. "Embrace, extend, extinguish" wasn't that long ago.
I mean, neither Ada nor Zircon are even on the lists, so in terms of mindshare, they are clearly blown out of the water by Rust (from the evidence you provide). To discount Rust based on usage when the alternatives being suggested don't even make the rankings is also a bit dishonest.
In fact, the argument "I think Linux should adopt rust for safety" makes perfect sense. Here's finally a safety conscious language that seems to be embraced by a larger community, and even the big tech players. Instead we get people suggesting arcane alternatives that may be technically better, but have a snowball's chance in hell to become commonplace any time soon.
In the meantime, Google makes extensive use of Rust in new components of both Fuchsia and Android and even rewrites some legacy components where it makes sense.
We can lead academic discussions about which language is safer/better/leaner/whatever-er, but the fact is that Rust has a larger and growing mindshare so this effort is unsurprising. For Ada, the solution isn't to try and prove to anonymous forum goers it would've been better choice if only people recognized the fact. The solution is to mobilize the Ada community to put the same amount of effort into the publicity and marketing (yes, the bad M word) of their ecosystem.
Ada clearly lives on in many safety critical systems, but judging by the admittedly biased topic frequency on HN and other technical sites, it has a tiny community who mostly keep to themselves. That's fine, but then don't be surprised when it's Hip Language X that gets the headlines and these sort of efforts.