SC is an idiotic choice and this is clearly Biden doing a favor for the guy who saved his ass in that state. Under zero circumstances should the first state primary be for a dark red shot that isn't competitive at all. This is basic politics. I agree with moving away from Iowa now that it's clearly becoming a dark red state...but why replace it with the black version?
If you want a first state that has a large black population that will heavily have a say in who wins, pick MI or NC. The point should be for the state to be somewhere where national party resources flood into the state and you prepare to be competitive there in the fall, for the general election. Obama dominating Iowa clearly helped him in the general election there in 2008. It essentially became a second home for him. I'd rather build that in a state you can actually WIN in a general election.