Polar bear hunting is regulated by how many $$ you want to spend to kill one. This bear was killed as a "trophy"...read the articles.
They are a species headed for trouble. We don't need to be killing them for "sport". They are dying quickly enough on thier own thanks.
I have had a few experiences with these bears. They are the top predator in thier environment (except for us humans).
As far as "the two most aggressive Carnivores"..well.......I beg to differ. I have never had a problem with a Grizzly, and have seen more of them than you could possibly fathom. (bears by nature are omnivores btw)
Your basic black bear can be much more aggressive and unpredictable in my experience. My experience with Grizzlies tends to lead me to believe that in general, they would rather get away from you.
I have had a couple of run-ins with polar bears (close calls), but they were entirely my own fault.
Polar bears, well..you are really just food to them, they don't seem to make much of a distinction between seal and "long pig". If it moves it must be food. Not really aggression, more like a smorgasbord.
Just as a point of interest, the most aggressive critter I have ever seen has to be the wolverine. These things are true "land sharks", and have a nice even temper (all mean and nasty, all the time).
So, there ya have it..RTR's picks for most aggressive Critters. Wolverines and Black bears.
Now, lets leave the Polar bears AND the Grizzlies alone. They have it tough enough as is.
cheers,
RTR