RKBA *should* be protected by the 14th, but it isn't. See, the Justices pick and choose which rights matter most, and RKBA hasn't been chosen yet. They can ignore enumerated rights while pulling unenumerated rights out of their butts, and somehow they still manage to sleep at night. Sucks but it's true.
I see nothing in my copy of the Constitution that says that it is the almost-Supreme Law of the Land, secondary only to Supreme Court decisions which run counter to it.
The Fourteenth Amendment makes clear that civilian disarmament is illegitimate regardless of when or whether the Supreme Court decides to recognize that fact.
BTW, no part of the Bill of Rights or Fourteenth amendment "protects" anything. All they do is inform people that certain things a government might try to do would be illegitimate. It's up to the people to decide what to do with that information.