Just need to make it shameful to fly it. Spam the internet with "patriotic" posts about our flag is Red, white and blue. Give people shit that their flag is disrespectful to our troops since the red signifies the blood of our armed forces that protect us. Make it the equivalent of kneeling for a flag.
Trying to shame authoritarians into doing anything is always a losing strategy. They're not capable of shame because they're not capable of seeing themselves as doing anything wrong.
Make em think it's gay then. Next pride parade should reappropriate it as a American LGBT Unity flag. They'll run, not walk, to the nearest fire to burn all their flags/decals/shirts.