But it kept attacking after it discover the other students. At least four were attacked and it went back to do extra damage to the first one it encountered.
That bear apparently didn't know the rules.
I'm no expert, but I am thinking the rule is referring to attack prevention as opposed to the dynamic when an attack is already under way.
In other words, I am wondering if things might have gone differently had the 7 hikers come across the bear as a group as opposed to the lead hiker running into her while effectively alone (assuming that is what happened based on that news article).