Many Cases Make Quick Law

The Supreme Court receives lots of petitions to hear cases. In the most recent term, they received over eight thousand and heard argument in 90 of them. So clerks are going to be very quick to reject cases that neither point to a circuit split nor present novel questions of constitutional law. So the fact that Elena Kagan devoted a single paragraph to denying cert for a gun rights claimant who wanted his conviction over turns means that the joker filing the petition didn't have much of a case. The Court had bigger fish to fry, especially considering that at the time Kagan was a law clerk, the prevailing elite view on the constitutionality of individual gun rights was spelled out by former Chief Justice Warren Burger:

[The Second Amendment] has been the subject of one of the greatest pieces of fraud, I repeat the word 'fraud,' on the American public by special interest groups that I have ever seen in my lifetime.

Longer article here.