Think its clear that the target is always worth taking out. You see this in the middle east all the time with the drone attacks. Because it is not your/our people dying we do not cry out. If the target is important I kill those people as well.
Would you destroy all life on earth to stamp out terrorism? If not, then even you must have a line. Do you have a number for us? How many innocents should die to maybe prevent the death of other innocents? This is why I say it's best to have an armed population. Let the people defend themselves.
Believe the number breaks down to optics. If you coul disrupt say ISIS once and for all, I would kill 2k ish innocent people to achieve this.
Sadly human lives are not all equal when we break it down. I could come up with numbers for all kinds of situations, but in the heat of the moment my numbers would most likely go up. I know I am in a minority in killing to stop a problem.
Interesting take. You might be in the minority with your position but I don't believe there is a right or wrong answer.