I seem to remember some Germans doing that with an Indian good luck symbol, swastika or something like that.
However, you can't deny that the rebel flag has been taken over by some pretty creepy racist elements in the 20th century. Most people associate it with these elements, not with the civil war.
Does that mean that the assuming masses should therefore dictate what symbols the rest of the people can use? History is complex and symbols have various meanings at different times. Just because some group hijacks the meaning of a symbol doesn't make it illegal to use. Otherwise Buddhists wouldn't be able to use the swastika or they would be accused of "hate crimes". I say let free speech rule.