The talk got downgraded due to one high-up person's serious issues with the talk, that person's concerns weren't made public, the identity of the person who had the concerns wasn't made public. Those are the facts. (Source: https://fasterthanli.me/articles/the-rustconf-keynote-fiasco...; ctrl+f concerns)

I admit that I assumed that those concerns were technical (i.e "issues with the direction of the compile time proposal"). I don't have evidence for that, because the concerns weren't made public.

Anyway, you're the one who's choosing to view their actions as sabotage of his work, I don't think I would characterize it like that.

EDIT: I want to add, it's possible that this person who had great concerns was dtolnay and that the concerns were simply what he outlines in this post (essentially just that it wasn't ready to be featured in a keynote; source: https://gist.github.com/dtolnay/7f5da4bf057b7c6d0d00c6bed306... ctrl+f "I expressed forceful skepticism"). I hope that's not the case, since that's a really weak reason to retract a keynote invitation weeks after it was given, and seems like it could be easily solved with some disclaimers... but we can't know, since, again, nobody has publicly disclosed what the concerns were which caused the talk to be downgraded.