1. The case was brought in the 9th Circuit because the challenge was to San Diego's law. San Diego is in the 9th Circuit. There have been challenges to similar laws in other circuits, which have largely upheld laws against carrying outside the home.
2. The Ninth Circuit used to be the most-overturned Circuit, but last year I believe the Sixth Circuit took that honor.
3. The Ninth Circuit gets overturned a lot because it has a lot of very liberal judges. But federal Circuit courts sit in randomly-selected panels of 3 judges, so you sometimes get a Ninth Circuit panel with 2 or 3 conservative judges. That's what happened here.
The Sixth!? I never would have guessed.