Long answer:

The point of the lawsuit is this:

SC state law allows electoral fusion, but the SC electoral commission prohibits fusion under under section 7-11-10 of SC state law if a candidate, seeks the nomination of and is nominated by one party then seeks the nomination of a second party, but loses the second nomination, the first nomination is invalidated and the candidate cannot appear on the November ballot under either party designation.

So why does the SC Electoral Commission interpret the law in this way? It it would prohibit the Republican primary winner, who subsequently tried and failed to get the Libertarian nomination, from appearing on the ballot as a Republican.

This is apparently a variation on the ’sore-loser’ principle, which presumes to keep spurned primary nominees from seeking to punish their inter-party rivals by splitting a party’s vote in the general election.

The different political parties represent more or less different ideologies; but still may have complementary interests. Electoral fusion permits a candidate to build a coalition of shared interest across part of the political spectrum. If the appeal to endorsement of a second party does not succeed, then the candidate still has a platform for political office. Except, apparently, in South Carolina, where the state electoral commission has interpreted section 7-11-10 to permit a party which rejects a coalition to negate the candidacy of another party.

Now if you are still with me after all that, then you might agree with me that the ACLU is taking up a case with broader implications for political choice in the state of SC than the initial post implied.