May I just present my limited knowledge? Ok.
Now, as I understand it, Grunther and his pack and all the intelligent deathclaws that can speak, are different from the ones in Fallout 1.
As I seem to recall, the enclave caught a bunch of Deathclaws, or maybe it was just Grunthar? Anyway, didn't the enclave, more specifically, that scientist guy that mutilated the poor robot doggy, experiment on grunthar, in an unnamed enclave base, enhancing his intelligence and getting him to speak? And then some escaped, but that guy and another dc was transfered to Navarro, where the white coat man found the deathclaws were playing dumb, and were alot smarter than they let on to be? And then you go to either kill that one dc or let him free.
So the inteligent deathclaws make sense, and are a breed apart, so to speak, from the deathclaws in fallout 1, and the wild dc's that you encounter in randomn encounters.
I hope I did not bore anyone. Feed-back would be nice.