when installing from a regular 2006.1 stage3 tarball, one cannot change to the hardened profile: hardened has glibc-2.4 masked, and the 2.3.6-r4 ebuild has a sanity check that prevents downgrading. Documentation should mention this to prevent people from wasting time. Perhaps the handbook should have a red note note the profile selection page that says "IF YOU ARE GOING TO USE HARDENED, YOU MUST USE A HARDENED STAGE TARBALL"
*** Bug 146491 has been marked as a duplicate of this bug. ***
Perhaps you should think about what you are doing before actually doing it.
This isn't really a bug. Try downgrading glibc on a fresh installed system ...