That means that if even 0.5% of non-Sámi Norwegians decided to suddenly identify with them, we'd swamp them. With whatever caricatured, romanticized, self-serving idea of Sámishness we came up with.

So I think the three (or is it two?) generations rule is sensible. Yes, you don't have to speak Sámi to be Sámi, but if not even one of your great-grandparents could speak Sámi, then your connection to the culture is tenuous enough that you should make some effort yourself (I.e. learn the language yourself) before you start getting into internal Sámi politics.