I think it comes back to the problem with defining terrorism.

For instance you can define terrorism as type of warfare. If you have cult which sees anyone outside their group as the enemy, and this cult is at a state of war. This explains terrorism.
Or if you have a nation state which conducts a war which does follow the provisions as describe in the Geneva conventions- e.g. targeting civilians, etc. This is terrorism.
Terrorism is a type of warfare. Genocide is a type of warfare. Mass murder without a political dimension is mass murder. Mass murder with a political purpose can be Terrorism, Genocide, or Conventional war: killing soldiers engaged in opposition is conventional war; killing a ethic or racial group is genocide, and killing non-combatants is terrorism.
The Geneva conventions are all about the nation state- they are "good" for the nation state- if one is interested in preserving the nation state one should follow them [it's not so much a matter of individual morality as things which are an advantage {or "good"} to nation states]. But what if one is existing in reality in which one does value the nation state and "your group" is at war [or you are simply dumb], then one will not neccessarily follow the geneva conventions.
Or if you are a nation state which "feels" that your nation state is so threatened by "something", you will not neccessarily follow them. Or with a indivdual soldier, if that person doesn't know what he or she is doing then it's quite possible to commit war crimes.

Now, what happens if a miltary force is following the Geneva conventions, but the media describes this miltary as not following them?
What happens if the media spreads terror acts by broadcasting them?
Basically this problem with terrorism is a problem because we are too stupid to understand the world we are living in.

Now what is democracy and what is the nation state? They are a recogition of reality, rather than a simply some *random* "good idea". They are also compromises to *something* which *might* be more ideal. But there can be almost complete certaintly that living in mud huts or "living in the past" are NOT this ideal. Viewing the past as "the ideal" is due to simply to a very poor understanding of the past and understanding humans in general.