Of course it is. A robber is trying to deprive you of your sacred rights. By seizing something that is yours without your permission, he is threatening your person. He is substituting his own personal force for morality and the law.
And if he does so openly and in your presence, it's an explicitly violent and tyrannical act. He has put you in the position of either losing your right to what you have earned and bought, or risking your personal safety merely to retain what you own and he does not.
Even 13-year-olds understand this. (Try to take their stuff and watch what happens next.) The handful who defy others' personal property rights are signaling that they are criminally insane, dangerous tyrants without decency, and there is no predicting what they will do next. If they won't desist without being shot, it's sad if they die, but if they insist on invasion, there is no alternative.
Giving jdege the benefit of doubt, he probably meant that in D.C. it is not “legally justified”. Note that in Texas, at night, on your own property, it is legally justified.