Drunk as a Skunk
There's a common cliche among leftists criticizing conservatives who insist on religious freedom: “Don't those morons know that this applies to their enemies?” On the contrary this started with a controversy about the religions of Native Americans, a group not normally thought of as right wing. The original law was passed with bipartisan support. It's the left that changed what passes for their minds about it. It looks like leftists are the morons who didn't know that this can apply to their enemies.
I'm reminded of the following quote from The Midas Plague by Frederik Pohl:
Howland was there, drunk as a skunk, disgracefully drunk, Morey remembered thinking as he stared up at Howland from the floor.
I suspect the protestors are concentrating on Indiana because it does not have a reputation for being far right. They think Indiana can be embarrassed into submission but they think South Carolina can't. If they were merely fund raising they would protest other states but they need a scalp.
A far-fetched but plausible speculation: A few days ago, it suddenly became well known that conservatives could also field an army of people with too much free time. The Left had to come up with a scalp in a hurry to maintain the illusion of inevitability and this was their best shot.
Advice for the Left
If you must come up with something to embarrass the right, I recommend hiring an illegal alien and claiming that it's required by the Biblical commandment to be fair to strangers (Exodus 22:21).