The instructions work. You do have to follow them exactly, and one easy way to screw up is by switching applications before the Open Scripts Folder step — it opens (and creates, if necessary) a folder specific to the active application when the menu is invoked, so if you've switched to the Finder, for example, you won't get the OmniFocus folder created.
The Scripts menu is not a menu with the label "Scripts" on it — rather, it looks like a little partly unrolled scroll:
It does not appear with the application's menus, but over on the right side of your menu bar. Open Applescript Editor, open the preferences, and click on the checkbox for Show Script menu in menu bar repeatedly while watching the menu bar. You'll see it appear and disappear. Once it has appeared, launch OmniFocus. While in OmniFocus, go to the Script menu and select Open Scripts Folder > Open OmniFocus Scripts Folder. This will create your scripts folder for OmniFocus in the correct place. The correct place for 10.6.8 is not the path you mentioned, btw, but rather ~/Library/Scripts/Applications/OmniFocus.
No need for rebooting to get any of this to work.