Honestly, I think there's a possibility that Rudy is educable on this issue, and that he may take this opportunity to reflect on wisdom of these judges, and begin a public shift in he position. When push comes to shove, Rudy hates crime and criminals, and is opposed to anything that helps them.
He grew up with the NYC mentality that anyone walking around the city with a gun must be a criminal (because 99% of the time that was true in NYC), and actually had a quite a bit of success at cutting the crime rate by his "nail 'em for the little stuff" policy, which tended to result in murderers and rapists getting arrested for jumping subway turnstiles, and then identified as people who were wanted for serious crimes, and also resulted in the younger set starting to get the notion that if even 'little" crimes could get you arrested and locked up for a while, big crimes were probably a really big deal. Amazingly, that notion simply didn't exist in the decades preceding Rudy's terms as mayor. There was so much major crime, the police felt they couldn't be bothered with "little" crime when there was so much big stuff to deal with, and the criminal class knew from experience that a little mugging here and there wasn't going to get them in any serious trouble.
Rudy knows the gun issue is a problem for his Presidential aspirations, and like any human being, is no doubt looking for ways to rationalize a shift -- both to himself and to voters. The combination of this exceptionally well-phrased ruling, and the fact that DC's draconian gun ban had clearly not made the slightest dent in its crime rate, could well provide him with an opening.
Interesting analysis. Guess we'll see. His current 2nd Amendment position certainly taints him in my eyes.