CentOS is the COMMUNITY enterprise operating system. If you want it to work with Zimbra, then at least take a moment to understand the issue and file a bug in CentOS's community bugzilla.
AFAIK, no one has done that yet.
I think jholder's announcement was poorly worded, but the advice is good. Ubuntu has a larger and more active community than CentOS. The Ubuntu port came from community members who demonstrated interest by committing work. If CentOS is to be seen as a viable community distribution, not just an imperfect RHEL knockoff, then you need to demonstrate that.
There was a time that Ubuntu was an imperfect Debian knockoff. The user community made it what it is today. Zimbra is not going to lead the CentOS community; they have other distros to support.