Rather than replying to old threads like this, you're better off search the Idea section for this Idea (or creating one) and then voting/commenting there. I'm (re)locking this thread.
Or better yet making sure that Guam ZIPs are NOT in the Tableau DB before voicing a complaint.
We do have post code coverage for Guam. The following post codes are available.
Let us know if these are not working or if you are expecting a different set.