In the very last paragraph, it references the Welcome Movie, thus indicating that the purpose of this hint was the Welcome screen (including set-up assistent).

What is wrong with simply going through the welcome routine, do the updates and then just reset that 'Welcome-bit'. Going through the set-up assistant really does not take that long.

So, the gist of the hint seems to me:
rm /private/var/db/.AppleSetupDone

Or does this not work after one went through the set-up assistant?

This technique, never creates a user (ID 500), leaving the configuration still in a "virgin" state. The receiver of the Mac will experience the same first use as any new Mac purchase, but not have to deal with the hassle of installing the iApps and all the updates.