I'm not an expert on Chechnya, so I'll concede that point. But here's the bottom line: were the bombers motivated primarily by nationalism, or by religion? From what I've seen of their on-line postings, it was religion.
We tend to label terrorists by nationality as well as ideological labels. Chechen muslims have proven themselves to be a type of special forces of islamic terrorism even making up a considerable portion of Bin Laden’s personal guard.
BTW I think its important to know where individual terrorists come from because not all are culturally alike and its often reflected in their behavior.
For instance, Chechens (And other eastern European muslims) seem to take special pleasure in targeting children.