Solved my own problem, but took awhile. Turns out all documents have to be closed before the texture cache will update.
Really? Given that most commands are run from within an open document, that seems of limited utility. Do you see a use for it?
I guess I'm a little skeptical that it's working as intended.
BTW, I just performed a quick test to determine under what conditions the Texture menu will update itself if a new texture is added. It seems that if the texture is added into the Configuration folder within the user library application support folder and the application is restarted, then the menu will be updated; otherwise, not. So in that light, fw.reloadTextures() may be an improvement over the application's default behavior, but not by that much.