As a citizen, I demand from my country that they stick up for me. The second I get the feeling the country's not doing that, I stop paying taxes. This isn't often talked about, but citizenship is a two way deal. And I absolutely can refuse to cooperate in any manner with the state and cause a lot of trouble. And when I'm not alone and can rally other people behind me, we call this revolution.
So no, it's not grasping. It's an ancient principle on which the relationship between ruler and ruled is built. That someone committed a crime doesn't change that relationship. Not in the slightest.
But then, you just want to see blood. You're really no better than IS yourself. Yeah, I said it. Don't get all riled up in your righteous fury. You're bloodthirsty and just want to be extreme. You don't have any investment in this issue. You won't see her getting hanged. Heck, you probably didn't even know who she was until this thread. But going "HANG THAT BITCH!" is what you do, right?