This poster image invokes the great quote of Martin Luther King Jr., whose words are in fact revered by this author and this poster. Unfortunately, the modern delusional masses have abandoned the original words of MLK and now leap to judging people by not just the color of their skin, but also the color of their flag (such as the Confederate flag).
In a truly tolerant, colorblind society, we wouldn't judge people by the color of their skin nor the color of their flag. But that society will never exist as long as self-incensed haters of historical symbols keep ginning up hatred for the particular symbols they don't like.
This poster is essentially saying to society, "Have you so easily forgotten the words of MLK and why we shouldn't judge people by colors and labels?" The political left in America today now contradicts MLK and claims they can judge people by the color of their flag. In fact, the political left is judging an entire geographic sector of America -- the South -- by falsely claiming that all southerners are racist, bigoted miscreants, merely because one crazy lunatic happened to post a picture of himself with this flag. (He was also wearing a Gold's Gym t-shirt, but I don't see any outrage against Gold's Gym...)
Of course, as California keeps collapsing, all those same people keep trying to relocate to Austin, Texas, but that's a contradiction they don't seem to mind.