The author needs to study the origins of the right to keep and bear arms.
While self defence is part of the God given right, the reason it was added to the Constitution is to protect the citizens of the US from tyranny. If uor government ceases to serve the citizens, the citizens have the right to change the government, by force if needed.
Self defense and every other moral use of weapons is included in the protection, as you noted. The Founders would have been shocked at the idea that a citizen might be prevented from keeping and bearing arms for his defense.