First, all of the discussion about pornography is irrelevant. The law only deals with violence. The 9th Circuit acknowledges that the government has broader powers to regulate pornography.
Second, violence in a work of art doesn’t necessarily make it immoral. So the law isn’t about public morality. Therefore, supporting the California law isn’t something a Catholic is required to do. A Catholic certainly could chose to support it of course. Rather, what this law is really about is the dubious theory that some parents and psychologies hold that playing violent video games causes children to act violently. Again, a Catholic can believe that, but they are not required to.
Third, applying this California law to books, paintings, and other art forms, shows how overbroad and bad of a law it is. The law would require branding of the Bible with the California warning label, and outlaw its sale to minors. Although other types of works might be banned as well, in its broadest application, the California law applies to games that have:
“killing, maiming, dismembering, or sexually
assaulting an image of a human being”
“serious injury upon images of human beings or characters
with substantially human characteristics in a manner
which is especially heinous, cruel, or depraved in that it involves torture or serious physical abuse to the victim.”
Numerous passages in the Bible would meet that two prong tests, include the Crucifixion, the stoning of St. Stephen, the book of Job, thereby triggering the labeling requirements and restrictions on sale to minors. Likewise, paintings, sculptures, etc. of those events would need to be labeled as well. So no cruxifixes, rosary guides, etc.
I am not saying there can’t be any restrictions on speech, but this is particular law is not a proper exercise of whatever government interest the government should have in regulating speech. When you give the government the unfettered right to restrict speech, there is a risk that it will use that power in a way contrary to liberty (and public morality for that matter).
FWIW, this isn’t an example of the 9th Circuit issuing a decision that is extremely liberal. Similar laws have been struck down in other circuits for similar reasons.