The Second Amendment was a necessary precondition of enacting the Constitution in the first place. Repealing it would mean not only the end of the Amendment itself, but also the end of the Constitution.
It would not, however, mean the end of the right, because the right itself pre-existed and is not dependent on the Second Amendment. It would simply legalize government abuse and denial of the fundamental right to self-defense, just like in Rwanda.
You are right in part. The "right" pre-existed the Second Amendment and the Constitution. Repealing the Second Amendment removes an explicit limitation of government power.
But the same logic which allowed the author to properly read the protection afforded by the Amendment, will operate to argue that the lack of a prohibition could in no way grant the federal government a power which it previously lacked.
One would have to argue that the ratifying states, which refused to approve the Constitution without a Second Amendment, had somehow overlooked an explicit power to disarm the people.
Here's an example which might meet the author's tyrannical desire:
"Amendment xyz: 1) The Second Amendment is hereby repealed.
2) The government shall have the power to infringe the right to keep and bear arms in any way that the Congress shall approve."
No government can be granted the power to repeal an unalienable right. The injustice done to a lion by removing its claws and teeth is the same injustice done to a person by infringing his right to keep and bear arms. Either lion or man is fully justified in opposing such injustice with the use of lethal force.