Sadly despite his young age he does appear to have been a nasty piece of work.
The aunt is quite right "you shouldn't have to bury your child". Perhaps if she and her sister had been more proactive in bringing him up then he wouldn't have been roaming the streets at 14 years of age with a gun in his hand.
Having already been charged with attempted murder I think it's fair to say that NYPD probably saved a few more lives by killing this kid.
BTW I totally agree with the commissioner, when you're in those situations you shoot to kill as your life is on the line.