It's a heritage thing and yet another example of the destructive breath holding and eye gouging on both sides of the issue that's led to some very contentious, grudge creating arguments and sulking. The local heritage folks feel betrayed for doing a good job for nearly a Century and getting crapped on by corporate.
This growing distrust and animosity was predicted as soon as Corporate moved from across the railroad tracks on E. Marginal Way So. to the Morton Salt Building in Chicago. What's fed the fires lately is the corporate penchant for elevating surplused drones from Long Beach to high positions in the company. Most old hands see this as putting the drunk who wrecked the Douglas machine right back in the drivers seat, the prime example was putting Stonecipher behind the wheel after he'd made a once proud company a smoking hole in aviation when there were a large number of more locally aware of how it works here, and worked well with the local folks, guys who'd clawed up the ladder just to get dumped on by an 'outsider' transfered away from LGB because their position as a 'chart boy' dried up.
Lots of those types were made managers or line Supers but had zero experience with any sort of 'touch labor', had never been on the factory floor, and never intefaced with the sweaty folks actually doing the work, given mobs of brand new just out of training non functionals and dropped onto the brand new 787 program when it was like trying to grab a BB in a running blender and inexperience on both sides of the issue didn't mesh, and couldn't find any common ground to start working issues 'this is all screwed up, we can't make 'it' work' 'well, I have a meeting to go to, do the best you can' to a group of 60 day newbies, a few experienced hands could probably made 'it' work, but those folks all got swept out the door in the previous drive to create a vast pool of lower pay grade 4's who would never be around long enough to make it to 7's or 9's as their years and knowledge grew, and initiative was not encouraged because, after all the new airplane would just 'click together'
so we don't need a lot of experienced guys who'll just tell us 'we never do it that way' which gets in the way of the Boeing 2016 plan where stuff all flows in from overseas and goes together like a really big model and we don't need a lot of people as the eventual plan for Boeing 2016 is to do nothing to the airplane except put a sticker on the F.E.D. frame that says 'completed by Boeing'.
So South Carolina is seen as a strong slap in the face to the long time heritage builders here, and they deeply resent the implications of it.