While your fun little hypothetical scenarios are interesting...they are just that, hypothetical scenarios. The fact is you don't know who will attack whom, with what weapon, at any given time.
And while I'll agree with your PTSD point, the solid fact is that guns are hardly the cause of PTSD...there are numerous other factors and situations that can cause it.
There were over 13,000 alcohol related vehicular deaths in 2006...it's perfectly acceptable to surmise that those drivers, after realizing they'd killed a person, or perhaps an entire family because of their drunk driving have suffered PTSD. So what are we to do? Outlaw vehicles and alcohol? Yes, that's the answer! Since those two thing (even independently) have the potential to be harmful and dangerous, should we take care of that potential by making laws against them? No.
The primary purpose of those things it not harm, it is enjoyment.
Sport shooting (and yes, that includes handgun sport shooting) is just like any other sport, football, baseball, car racing, skiing, etc. Every one of those has dangers inherent with it...how many sports related injuries are there every year just in the high-school level? Yet we see no need to outlaw those activities.
The points you're using to argue against firearms are the same arguments I could make fit nearly anything...the gun control we have in place now is perfectly sufficient, and saying that guns, or handguns in particular have no purpose other than the killing of another human being is not only false, but it's also completely ignorant.