Pretty clearly, they decided that it was safer to not take this to the Supreme Court, which would strike down restrictive concealed carry permit laws across the U.S.
UPDATE: My mistake. I knew that the Supreme Court had denied cert in the 2nd, 3rd, and 4th circuits. I just plumb forgot. There is a 1st Circuit case still working its way up, I think. In the meantime, the California Attorney-General hyas filed as an intervenor, asking for an en banc review.