Right....but your user shell has nothing to do with shellshock. Shellshock involves things like Apache invoking system calls that need a shell, and those system calls don't care what your user shell is. They care what /bin/sh and /bin/bash are (or wherever your system shells live, it's /bin for OSX).
This guide is claiming that updating your login shell to bash via Homebrew will mitigate shellshock, which is flat-out wrong, and dangerous to boot.
OK, but nothing in your comment implied that you were talking about the "Shellshock" vulnerability. I believe that a very recent OSX update patched this vulnerability, anyhow.
Oops, a very good point. I should have mentioned that right off the bat: my issue was with calling this a "hacker's guide", when it contains a pretty blatant security issue.
This guide is claiming that updating your login shell to bash via Homebrew will mitigate shellshock, which is flat-out wrong, and dangerous to boot.