To claim that this means NAT provides NO security is simply ridiculous.
On a technical level, NAT does absolutely nothing to protect you. It simply translates one ip to another. Take a typical SOHO internet router for example, it can use a specified IP for a DMZ. That turns off the filtering rules, (they are what protect you) while NAT is still running.
...The computer behind NAT can't be port probed from external address or act as a proper server, big difference.
Those functions are provided by routing/filtering. NAT by itself does nothing to protect you. An open NAT box will send everything to the designated IP.
To thine own self be true. (If not that, at least make some money.)