I put up a meme from Pholosipher on the Book of Face using the recent Miramar shooting. The gist was that the when people say I should give up my guns because only the police should have guns, this was a prime example of how not only the police have no duty to protect, they will take actions that directly threaten your life. Such as shoot at a hostage or take cover behind occupied cars.
Two of my real life friends then jumped on saying that in this instance, would an armed citizen have made any impact or would they have just been shot? Considering Southeastern Florida police performance over some recent high profile incidents, I would concede that in this instance drawing a gun would have been a bad idea. I also would advise that being in a similar situation, the people in the cars do whatever they possibly can to GTFO, including leaving police without cover. After all, if they have no duty to protect you in that instance (and are in fact hazarding your life), you have no duty to offer them protection. Your mileage may vary depending on the particulars of the situation as well as your personal morals.
The main point of this post is the dangers of the non-sequitur. If you are attacking an argument, make sure you are attacking the actual argument, not some side issue that wasn’t brought up.