How is that any different than a felon saying that witnesses, police, prosecutors, or the judge made a mistake and convicted him wrongly? Because, you know, they never make that claim...
She was involuntarily committed to a mental hospital, which means she's prohibited from owning or being in possession of a gun. There's a big push right now -- especially among pro-2A folks -- to address the mental health aspect of spree killers rather than gun ownership. So California ran a computer program and started addressing people who were illegally in possession of firearms.
Now, you can disagree with whether those people should be prohibited from owning firearms, that's fine. But I would submit that in the current political climate you'll find little support from either the Left or the Right for the proposition that people with a history of serious mental disease should still be able to own guns. Same goes for convicted felons... that's the law of the land and even the Heller decision alluded to it as constitutional.
If it's the running of the computer program that has folks up in arms against Sean here, I'm pretty sure Sean understands better than most of us that the government is capable of making a list of people on one day and then sending forces out to deal with the people on that list later on. Some of you seem to be suggesting that Sean's in favor of gun registration, and I haven't seen him say that.