Keep Portland Weird's website, which KATU may or may not have consulted in producing this little gem, spells it out in pretty simple, un-pervy language:
Keep Portland Weird is about supporting local business in the Portland Oregon area. We want to support local business because they make Portland stand out from other cites and make it a more unique place to live. They do this by providing consumers a wide range of products that represent the different cultures that make up Portland. Local business also have pride in our city and are driven to make Portland a better place to live and enjoy.
The bumper stickers even say "Support Local Business," fer cryin' out loud. Hard to find that very threatening (unless, for example, you're a global coffee chain named after a Melville character--or, apparently, KATU).
Commenters on the thread also note that "Keep _____ Weird" didn't begin in Portland. To find out its true secret origin, you'll have to go to the OMI post.
(Bumper sticker image via Keep Portland Weird. Suggested retail, $2.00.)
(Cross-posted at LO.)