Do I look like I need YOUR help ?

Heller vs D.C. establishes the right to own any gun commonly used by law abiding citizens. Period.

It certainly will in the hands of a responsible person, such as, oh, I don't know, perhaps, say, a security guard maybe?

So, the original post suggests that ownership of a rifle negates the need for police.
I countered with a statement saying it does not.
Your counter to my statement is that it will do wonders in the hands of, say, a police officer, therefore reaffirming my point that police are still necessary.

A person who is responsible and competent with a firearm probably won't need the police to protect their home. And I mentioned a school security guard: that's essentially a policeman assigned to protect a school.
Thus, police are necessary overall, but one person with a firearm can probably protect their home from a handful of intruders.