I can't say I know much at all about Christian Identity, but if it's just living apart like you say, that seems a lot like the Amish and Mennonites are doing and that doesn't bother anyone.
If they want to force others to live apart, then that clearly crosses the line.
So ... don't by any stretch take what I said as what they are. Those have just been my impressions from the little I have heard and read in passing.