I think this can all be cleared up by one simple statement.
We do not have the right to never be offended.
If somebody calls me a cracker, and I get upset, whose fault is that? Mine for getting mad, or his for saying it? sure, it may have been wrong--well, not against a white male, but anything against a female or a black or hispanic or Asian would have been wrong, but what are we going to do about it? Are we going to sue everybody who says something we don't like because, oh, God forbid, somebody might could be offended by it? Learn to deal with it, we're all going to have to put up with people we don't like, and with people who don't like us. Shut up, do your job, and get on with your life. Whining about this--this and any other seeminly offensive remarks--will only add fuel to these people's fires. While what he said was correct, he worded it very badly. Don't like it? Don't sit next to him at the lunch table.
EDIT (ADD) : Trace Native American heritage back far enough, and even they immigrated from the Bering Straight. Face it, we're all descendents of immigrants, and I'm as much of a native American as anybody else. I was born here, I'm native.