It's OK to fork a project if it's dead or if its maintainers are too slow/abusive/unresponsive. Nobody really argued that forking glibc by Debian was a hostile move because glibc's maintainers were well known for their, shall we say, nice demeanor. However, in this case udev's upstream is responsive and mostly sane. I've been following udev's mailing lists and it appears that they have a normal working relationship with distributions.
Well, udev developers do appear a little bit unstable and it looks like they enjoy conducting cruel medical experiments on unsuspecting users. So maintaining official stable _branches_ of udev with backported fixes and updates would be great idea. Perhaps even a branch with some additional patches for a separate build system, etc.
But that's not what eudev does. Its developers basically took udev, made a few dumb changes (kmod revert), changed license and sticked their names all over the project.