If they didn't rage, minks would have little to differentiate them from squirrels.
In the wild, minks are carnivores and predators. I doubt they would attack animals so much bigger than they are (such as a worg), but they will put up a worthy fight when something big attacks them.
As far as the AI, though, is if you toned down their aggression, then they would flee (and die, like deer do). Minks are far more likely to survive by making a predator pay too high a price to kill them, than by trying to escape.
For example:
The greater problem is that fleeing means whatever is fleeing can be attacked with impunity. A mink can kill a worg because the stupid worg just keeps running and giving the mink free shots at it. But that's a mechanic that AFAIK is widespread, if not universal. (My PCs have killed many a foe--e.g. bonecrusher ogres--that would have done better to stand and fight, rather than run cowering into a corner and let me coup de grace them with a bow.)
