Facebook has been using it internally for a long time. It would make no sense for them to rename the tool for open-source release just because a naming conflict exists, unless you'd prefer they just not release it at all?
We typically do rename before open sourcing and intend to avoid namespace collisions. E.g. Litho was not the original name of that framework either.
I am familiar with most of the other tools mentioned here (e.g. SonarJava) from my time doing Java development outside of Facebook and never had a collision in my head because this project is not actually a library or tool for Java. It's a standalone Electron app that works on iOS and Android for debugging purposes, the only Java part is incidental in the Android app (and could be Kotlin or C++ or whatever you want).
That's a bad example. Gerrit is not a new name for Reitveld, it's a totally new implementation (with similar inspiration). And both of those were publicly released under those names.
It can and has been done multiple times in the past - AsyncDisplayKit -> Texture is the one that immediately comes to mind as it happened after open-sourcing.
