I can't help but think if the guy had called the APD and said something to the extent of "Hey, a bunch of teenagers just tried to assault me, I got scared and showed them my weapon and they ran off, would you like me to come in and make a report?" he could have advoided the whole thing. Sure he was within his rights, but anytime you use a weapon it helps to be the first person LE hears from.
FYI, A similar thing happened to me a couple of years ago (one guy in a dark parking lot), and when I called and reported it, TPD just took my name and contact info, and told me to go home over the phone. It was no big deal.