The intent was unlikely racist. This said, if racism was not so endemic and institutionalized as it currently is, then the overly sensitive reaction to this particular photo would likely not arise.
For every one act of egregious or frivolous “PC” behavior that occurs in this country (and it certainly occurs), there are countless undeniable and blatant acts of racism, sexism, and various types of chauvinism...I'm in North Carolina; I know first hand.
As for the photographer’s responsibility, well, ask the one who took a photo of a crucifix emerged in urine; lots of complaints about that one, particularly by folks who are now the ones most fed up with all this PC crap going around.
But then again, it’s not really about being PC or not, but instead who has a right to insult someone, and who doesn’t.
Be aware of the environment and your audience, realizing that even the most innocuous thing can trigger public dissent…example, an obviously Christmas decorated cup is, to some, not Christmasy enough because it is not adorned by enough ultimately secular symbols.