That project is not Python 2 though, it added features that made it incompatible with both Python 2 and Python 3. Just look at their effort to add wheel support.
Any project that forks changes name:
nagios -> icigna
mysql -> mariadb
NetBSD -> OpenBSD
FreeBSD -> DragonflyBSD
Python -> PyPy, Jython, IronPython
It would be crazy for them to keep the same name and not be compatible. It would cause confusion and also lead to increase of support tickets in wrong bug trackers.
In those cases, the original project lived on. Here Python 3 is the incompatible fork, but because the technical fork is done by the folks who control the name and who want to shut the old thing down, so the compatible evolution of Python 2 had to change the name.
Any project that forks changes name:
nagios -> icigna
mysql -> mariadb
NetBSD -> OpenBSD
FreeBSD -> DragonflyBSD
Python -> PyPy, Jython, IronPython
It would be crazy for them to keep the same name and not be compatible. It would cause confusion and also lead to increase of support tickets in wrong bug trackers.