All I can say is that anyone who thinks a missing or altered safety device on a gun used in a shooting won't be an issue in court should consult an attorney for a professional opinion. I have asked several lawyers about this matter and they all said the same thing. They would smile broadly if they found out that the guy they were suing had disabled the gun's SAFETY DEVICE (and that's exactly how the lawyer will explain it to a jury made up of people who have never touched a gun in their lives).
If it hasn't happened yet, it's only because such a modified gun hasn't been used in a shooting resulting in litigation.
If you think that I (and the attorneys) are full of BS then go ahead and remove the safety. If you don't mind losing a huge lawsuit then go ahead. If you don't mind spending $50,000 - $100,000 in legal costs defending yourself in court then go ahead.
Before my current job I worked in the insurance industry as a claim handler, major claims. Product liability lawsuits mainly. I reemember one suit against a major electric tool manufacturer. It hinged on the fact that the tool didnt have a safety device that other tools on the market had. It was a very old model of electric drill. The suit alledged that because one other brand of drill made by another company in 1959 had double insulation, my insured was negligent for not manufacturing their drill with double insulation instead of a grounded case. The year of the suit was 1992, the drill was made in 1959, and the owner who was killed by electrocution, had defeated the grounding feature by replacing the original grounded cord with a lamp cord. They won the suit when it was the owners fault, for replacing the cord, and laying in the wet grass. We appealed, and settled based upon contributory negligence which the jury had failed to consider, for a much smaller sum.
The point is you can be sued for anything, if you use an old gun when you own a new one with a lock they could sue you for that. In a self defense shooting the lock is irrelevent becuase you intended to shoot the plaintiff.
In my state I dont have to worry about this because unless you are arrested and found guilty you can't be sued for a self defense shooting. Period. We have a law that is very specific about that.
In an accident it could be an issue, but like the drill case above, your old guns with no lock could be just as much of an issue.
If I have a trigger job that could be an issue, If I belong to a gun club or two and practice weekly that could be an issue, If I partcicpate in IDPA IPSC that could be an issue before an uneducated jury (practcing to be a killer) If I take Massaad Ayoob's class doesnt that show that I am training to be a killer as well? Carrying hollow points could be an issue too, so could FMJ.
JMHO YMMV