Ulrich Drepper writes a lot of VERY good explanatory papers, and some great documentation as well as doing a huge amount of work on critical infrastructure we're ALL using. He's also insanely busy.
Even with this fork, he'll still be doing a large amount of the work going into each eglibc release, via merges with glibc upstream. If eglibc takes off and proves to work well, he'll hopefully consider merging things from it once they've matured that he might not have been too happy about introducing untried into glibc.
That sounds like a win to me. I just hope these don't become antagonistic forks where work is wasted on duplicating already-completed fixes and features, and on pointless flaming.