Turnabout is fair play. South Carolina is an open primary state too. Maybe some of us should vote for Kucinich or Gravel there.
The difference is that there’s a competitive Republican primary in South Carolina, and our votes are needed there. Kos suggested this plan for Michigan because the DNC is not going to seat the Michigan Dem delegates anyway, in retribution for Michigan having moved the primary date up against the terms of a prior agreement. As a result, the major Dem candidates aren’t contesting Michigan. Since their votes in the Dem primary are essentially meaningless anyway, Kos recommended Dem voters messing with the Republican primary.