I'm not a self defense attorney. My thought on this is that it does lower the bar for establishing the defense in a civil suit because it makes the criminal defense apply. In a criminal trial, you need to show you had a reasonable fear for the safety of yourself or another (big simplification). In a civil case, you must rebut evidence that you acted negligently.
I've never done cartwheels over "civil immunity" statutes. The reason is that you will still wind up in court to litigate whether immunity applies. They do lower the bar a defendant (the shooter) needs to meet to establish the defense because the criminal self defense rule is broader than but you will still wind up in front of a judge or jury. The lower bar may help a defendant in close cases, but he'll still be on the hook for all the expense of defending himself.
