Having 5 men with guns kill a bunch of people is a lesser evil than declaring all out war on a religion. Many many more innocent people will die if that happens. If you have 5 of these extremists in your city, you have hundreds more who would become that if they were cornered on account of their religion.
It's hard to get around the anger that comes with this bullshit, but that's the fact that the people who are running the show are dealing with. How to combat the situation with as minimal losses as possible.
It has nothing to do with how many guns are on those streets, either. More people would die if the guns were on the streets with the citizens. The numbers just get worse.
This idea that apathy is behind inaction is the typical response of someone who cannot separate anger with the straight up statistics that come with any action.
Nobody can stand up and say that losing a couple of hundred people here and there is acceptable, but the fact is, many many more of our people would die with war. From that point of view.. it kind of is

There is no doubt Islam IS a problem. None of like this religion.