"terminally different" does not mean "it's hard enough to come to agreement that at least one party resorts to violence".

Though I guess there's a point hiding in there. If two random people are stranded in the desert with enough water for one to survive, their value systems will both say "I want the water", but they point at different "I"s. Even if they manage to cooperate and draw straws, there's still room for the stronger to just take it because of "incompatable value systems" - even if the value systems have the same fundamental structure after abstracting away specific beliefs and positions.

However this definitely doesn't apply in modern day relationships and I very much doubt that it applies to terrorists either.