Because that is who the left identifies with. We project what is "familiar," which is further evidence that this "Sgt USMC" is nothing of the kind.
Pure BS if you ask me, and the dummies reading it, fell for it hook, line and sinker...
Yeah, I tend to think this whole "message from the Sergeant Major" is nonsense, too.
But it does bring up the interesting discussion about just what we ought to do were such a drastic situation happen. We don't like to think about it, and I think only an idiot hopes it would happen, but all the same, a civil war in America could happen. We're not gods on this earth, immune from the trials of other men, after all.
Personally, I think that if such a thing were to happen here, it would NOT be because "right wing Tea Partiers" started it. It would happen because of one of two things (or perhaps both, working synergistically):
1) The government reaches a critical point where the mask comes off, and it just doesn't have to pretend to operate within the rule of law anymore. In such a case, expect random checkpoints, confiscation of firearms, shuttling of potential troublemakers to concentration camps, and neighbours who just "disappear" one day, never to be heard from again. Expect these, in return, to provoke a violent response from the remaining citizenry, or at least a good portion of it.
2) The government finally goes so broke that it can't even borrow money to write out IOUs anymore. At this point, among other things, the welfare checks will stop going out, and expect hordes of, ah, urban dwellers to suddenly figure out that the benjamins ain't coming in anymore, and they're gonna need food after the local Burger Kings and McDonalds have been picked clean. The country and suburban folks better have a plan for defending themselves in an organised fashion.
Either way, it's an ugly scenario in the way that only civil wars can be ugly. Nobody in their right mind hopes for that. that's why we have a legislative process and voting, to circumvent the necessity for a civil war every time we want the government to change.