After the fact it is much easier to armchair quarterback the event, but the young guy did not have that option that night. It is way simple to say, "He had too much gun" after the fit hit shan, but how does someone know that prior to the incident? Besides maybe the kid had small hands. There are just a lot of reasons why the AR-15 was a better choice BEFORE everything happened.
As a father and a husband, I want my family to have every advantage if something similar were to occur. IMHO, what most people here are saying is that while the AR-15 isn't the only gun that would have done the job, it would be among the first choices of available guns. Further, there is no question that the AR-15 did not leave the kid at a disadvantage. I don't think many gun owners would like to be without that choice.
Note to readers: If you live in New York state, home invasions should no longer be a surprise. You should expect them.
"When Faith preaches Hate, Blessed are the Doubters." - Amin Maalouf