Is that a good thing?
My theory is that he's collecting all the (formerly non-voting) racists. I think killing a terrorists family is a bit extreme. It very much goes against the rule of law and it's basically taking things in the wrong direction. Terrorists usually are doing something their families wont approve of.
Donald Trump on terrorists: 'Take out their families' - CNNPolitics.com
You're also going to create even more enemies of the US state, as if it doesn't have enough.