With RKVs, since they don't use FTL technology, they won't create the same sort of active signature a FTL version would. Maybe you could go so far is use stealth technology to make a terror/strategic weapon.
The whole wormhole this is a neat idea, but then we're back to square one. If you could pop open a wormhole in close proximity to a planet without alerting it, you could simply use the wormhole itself as a weapon for atmosphere deprivation and such, and would need a RVK.
That whole wormhole thing got me thinking that the real issue here is balance, not theory. In theory, at their current technology level the SA should already have a hundred different ways of killing a planet (anti-matter, RKVs, hyperspace shunt, hyperspace kamikaze, bioweapons, chemical weapons, aether weapons, wormholes, etc), yet none are actually used. I think due to the whole worry about turning SA into a giant Cold War revolving around strategic weapons, while ships and armor become essentially obsolete.