How many times a year to you hear about a police sniper shooting a hostage taker because they believe other people are in imminent danger? No arrest. No charges. Just a quick kill because there was no other way to prevent them from killing someone. Think of the Predator as a sniper on steroids and again, if there is no other way to prevent the taking of even more innocent lives, why not use it?
Wow, conflating "plotting" with the "imminent danger" of someone holding hostages with a gun to their heads. Even in hostage situations, they attempt to talk the guy out, and you're jonesing to blow some guy up because he has a map and some plans. There is no moral difference between you and some guy proactively going out and shooting a politician because the politician is plotting to pass a law giving politicians free use of deadly force. You've ceded the high ground.