Practically, of course not. Within the New Republic's convoluted moral thing, where does your hypothetical leave us? There's an added layer -- governments have an obligation to their people. The Israeli army and coalition leaders have a duty to their citizens, which they clearly don't think extends to Palestinians. That's nothing isolated to Israel, either. People after people have followed a similar moral trail throughout history. What's interesting is that Tories protecting British spies (and soldiers) during the American Revolution offers a similar case study. The scope was far too small to give an answer to your question, but it's still worth thinking about.Would Israel use the same rationale, if they were killing Israelis instead of Palestinians in the crossfire? Would they kill Israeli civilians to achieve the same goal?
What if terrorists gained a foothold in say, the American South? With as little as 1% of the population supporting them, they could probably find shelter and weapon supply.