everything about early state primary/caucus traditions is older in iowa, because iowa being important was a thing before any other state being early became a thing. iowa already gets by far the most attention from candidates, and aside from the black and brown forum, iowa also has, off the top of my head, the state convention, the state fair (an entire rough ridin' week), the steak fry and the dinner thing you went to as events that are considered mandatory for candidate attendance. aside from tomorrow, sc has just two, the fish fry and the state convention.
it is logical that south carolina try to ensure the candidates pay a little more attention to them and entirely fitting that they ask candidates to spend mlk day in the early state with a sizeable black population. so yeah, sorry iowa, if you can't figure out a way to schedule that permits candidates to attend both events, candidates absolutely should prioritize sc and sc voters should take note of any candidates that don't.
and the idea that iowa wouldn't alter the schedule because they wanted time to edit the thing for tv is frankly insulting on it's own.
as far as my ignorance goes, i didn't know about the tighter turn around for klobuchar compared to the other candidates and that's at least a better excuse than buttigieg's.