It was wrong of them to act like you're ignorant or anything, but it stood for a lot more than 'southern pride'. Like General Lee, I'm glad that the Union won(yes, Robert E. Lee said he was happy that the north won) because it abolished slavery QUICKER. Again like Lee, I don't agree with the federal sovereignty ideals. I believe states should rule unto themselves and the federal government should always take a back seat in politics.
It's not about hate to everyone who displays it(I don't display it--it's on the cover of a story I'm writing, but so is the American flag). It's about a heritage, a political ideology, and a means towards coming closer to achieving a truly sovereign country by allowing each member to be sovereign unto itself. Where I work, in a small town in southern Texas, there are black people who display it. There's occasionally a short rally where about a dozen pickups meet at one end of town and drive to the other, all covered with, and flying, the Confederate flag.
There are many, though, who use it as a symbol of hate, and they ruin it for the rest who fly it.