According to the discussion in /r/rust/, one person falsely claimed that they were speaking on behalf of Rust team consensus and the RustConf representative they talked to got burned by taking their word for it rather than asking for confirmation.
I'm still trying to find confirmation of which message it was though. If it was the initial invite that was "issued without authorization", then the revocation would make more sense.
They abuse their influence to demote a keynote selected by the agreed-upon keynote selection scheme, because it makes them “uncomfortable”.