To provide some more detail, the original plaintiff (Peruta) was denied a concealed-carry permit in San Diego, under their highly restrictive laws. And California doesn’t permit open carry under any circumstances. The combination of the 2 effectively represented a violation of the 2nd Amendment, as it eliminated any possibility for a citizen to exercise their 2nd Amendment rights. Had the original ruling been allowed to stand, either San Diego or California would have to give - and you know who would win that.
The San Diego no-issue laws would necessarily become shall-issue, and any other jurisdictions with similar restrictions would have to follow the precedent - effectively making California as a whole a shall-issue state.
With the ninth circuit’s reputation as the most liberal in the land, clearly there are enough judges on the court that believe they can find some daylight here, preserving both the ban on open-carry, and at least something substantially less than shall-issue.