I keep hearing this...
In certain circumstances, I can see where a lock could be a useful feature with small kids around.
I have yet to be able to come up with a single creditable scenario where having a
loaded gun with a built in lock, or an exterior lock (trigger, etc.,) is superior, or even preferable to having the same gun properly inside secure storage, or
unloaded.
I think it is a false idea that having a gun loaded and locked is better for rapid response than having the same gun locked in something, or empty and ready to load.
I think I would probably be faster loading a revolver with loose rounds than I would be finding a little key (which is kept where? ) and getting it in the little keyhole under extreme stress.
I am confident that I could even load a revolver in complete darkness (particularly with a speedloader) faster than I could unlock a loaded gun with an internal lock.
If you have a home situation with undereducated children, or irresponsible idiot adults who might have unsupervised access to your gun, simply do not leave it loaded. Its not rocket science or brain surgery level thinking. Unloaded guns are only dangerous as impact weapons. A 6 year old or your idiot brother in law can hit someone with your gun, but they cannot shoot anyone with an unloaded gun.
If your gun has to be "instantly accessible" for you peace of mind, wear it. Otherwise forget the lock, and especially forget locking a LOADED gun.