I agree with you that the Sup Court does not properly, or legitimately have this power, but the sad fact is that in reality or practice they do because the other two allegedly coequal branches have let them have it.
Just consider how many radical, out-of-the-mainstream decisions the Sup Court has handed down in the last fifty years or so. While they havel helped to galvanize the social conservative base and thus help the GOP win many elections, they have sadly not resulted in much change at all. We have not had a President or Congress bold enough to pull an Andrew Jackson and defy the Court. We have not had Congress exercise its jurisdiction limiting authority. Instead we are left to the pathetic state of hoping that, this time, the latest Republican president hasn't completely F'ed up in picking a new SCOTUS judge. And unfortunately for us, they do screw up as much or more than they get it right. I mean, Reagan and Bush I combined to pick just two good judges out of five opportunities!
So I am doubtful that the American people would rise up raise hell if the Sup Court definitively gutted the Second Amendment and rendered it virtually meaningless. I even fear that such a decision would, the longer it stands, serve to push public opinion towards the garbage collective right view. It has happened with abortion and Roe; it too was a radical decision and outrageous usurpation of power by the Sup Court, yet today most people voice what is at least marginal support for the decision (though yes, I would fully agree with the assertion that this due mostly to the lies and distortions of the Left and mainstream media).
So the fact that the Sup Court does not legitimately hold the power it has given to itself if meaningless so long as the rest of the govt and nation dutifully obey all of its orders as though they were the word of God.