The RNC is dead wrong on this plank. It would sully the definition of the first amendment and import a tinge of fascism into our constitution. Its proponents are well-meaning, and they're often military or ex-military, but this is a civilian issue, not a military one.
As Robert Bork points out, the SJC ruling regarding the flag overturned precedent back to the founding fathers. Nobody prior to Griswald would have contended that flag burning was constitutionally protected, no more than sodomy.