Gettysburg mug makes waves

The Rebels are shown retreating under their own flag, depicted on a mug. They have, in this illustration, been beaten at Gettysburg.

People, seing the flag but not making a contextual distinction, are upset. Is it a Southron statement? The mug owner has other problems but the mug has become a flashpoint.

The story here. (The comments under Eugene Volokh's posts are hopeless.)