Or that might end up as some boolean value in about:config like "SetMoronicBaguetteCensorship" that even a gonk can remove in 2 minutes with a tutorial.
FOSS stands for "free open source software. Open source means the code for the software publically available for anyone to see. A fork is when someone take a project like firefox and clones it (copying the source code), make any chsnges they want (such as removing the in-browser block list) and re-releasing the app.