It also speaks to an absolute failure of governance. If I missed an important email on a FreeBSD mailing list, you can bet that a dozen other people would see it and either poke me about it or just go ahead and act upon it themselves.
The fact that RMS missed an email and nobody else did anything about it either is a sign of an absolutely dysfunctional relationship between the project and its leadership.
If I had to guess, the actual GCC maintainers[1] had no interest into integrating a very large codebase into GCC which would duplicate a lot of its functionality.
LLVM could have been integrated under the GNU/FSF umbrella as a separate project of course.
[1] since the egcs debacle was resolved, RMS has had very little control of GCC
The fact that RMS missed an email and nobody else did anything about it either is a sign of an absolutely dysfunctional relationship between the project and its leadership.