Technically any unintended discharge of a gun is a negligent discharge because the user isn't following the 4 rules of gun safety. The trigger dongle makes a glock drop safe, but not safe from idiots putting their finger on the trigger (where most NDs happen).
I agree - that's why we should not allow Presidents, Governors, or any other public figures to speak at any event because they clearly also come with a heightened risk to everyone there.