I think it could be different timelines. The Google projects interested in better C++ interop have been around for 2 decades - Chromium and Android. They’ll be ok if the effort bears fruit in a year or two.

The latest on this project is in this update - https://github.com/rust-lang/rust-project-goals/issues/388. They’re working on it, but no progress yet.

I think the author wanted something now, which is a completely acceptable reason to start his own project.