The young protesters aren't "savvy"; they just didn't know that repealing the Second Amendment was possible.

https://www.washingtonpost.com/opinions/repealing-the-second-amendment-is-a-dangerous-idea/2018/03/28/ab194138-32af-11e8-8bdd-cdb33a5eef83_story.html?utm_term=.a18a98e781a7

By "brilliantly effective," what the writer of the Washington Post article is describing is a compromise that the March For Our Lives people didn't know that they don't have to make.  

I also think that perhaps I don't understand some of the writer's argument.  Is he saying that you have to have a constitutional protection of the right to have guns before you can pass laws saying that people can't have guns?

If that's what he's saying, then I have to disagree with his lack of faith in Congress.  I think that Congress could figure out how to pass laws such as "You can't have those guns; give them to the police so they can dispose of them."