I'm not even really sure Muschamp was their "4th choice." He might've been the 12th or 14th choice. Its particularly embarrassing because they had months to conduct the search and still came up short. Justin Fuente chose Virginia Tech over SC and Tom Herman decided that staying in Houston was better. It looks like RichRod wasn't genuinely interested either and was using SC to get a raise, as well.
I can see some logic to hiring Muschamp, and he's not going to be a "disaster." Really, he left Florida in better shape than he inherited it; he just wasn't a very good head coach. I'm not convinced that offense was his only problem either. He just doesn't strike me as having the personality to "lead" and act as "CEO" of a major program. He recruited reasonably well at Florida but never could everything out of his players; and it seemed like they were frequently lackadaisical about non-rivalry games. (Seriously, am I the only one who noticed his teams showed up for Tenneseee, Georgia, and FSU, but not Vandy, Mizzou, SCe, etc?) Of course, while recruiting was decent at Florida under Muschamp, it's a lot easier to recruit in Gainesville with the flagship program in one of the best states for talent in the nation than it is in Columbia, SC, where you're playing 2nd fiddle even in your own state.
Muschamp might get SC back to some 6-6 and 7-5 type seasons, but I'd be shocked to see SC at 10-2 with a top 10 ranking again.