This:

If you have administrator privileges, you must fix an Apple-introduced problem in Mac OS X 10.5 Leopard by executing the following command, or BASH and Zsh will have the wrong PATH when executed non-interactively.

sudo chmod ugo-x /usr/libexec/path_helper

Is incorrect. Users shouldn't disable path_helper.

The problem is OS X is that it comes with /etc/zshenv that uses path_helper. However, /etc/zshenv gets sourced for every zsh shell, even non-interactive. To put a stop to that, simply:

sudo mv /etc/{zshenv,zprofile}