> downgrade was not racially motivated, thankfully Who would have suspected this was racially motivated? Not to defend any actions by anyone, but a keynote is an unusual place to talk about experimental feature a language is considering (unless it's a small component of a bigger update/forecast). That said once the decision was made they should have gone through with it.
It's not that unusual. Herb Sutter's 2022 CppCon keynote was on a prototype redesign of the C++ syntax/language.
If your language isn't intending to just remain stuck forever in its current state, a conference is a reasonable place to explain a proposed direction so that other people know where you think it should go. Not every talk has to be speculative, but a speculative keynote seems fine to me so long as it's obvious that we're not in an alternate dimension where this works in Rust already, which I see no sign JeanHyde was intending.