I kinda agree with you but what would the adult have done?
The kids should have been walking in a tight line and waited in a group on the other side of the creek before moving on.
Instead the lead kid went out of sight so the bear saw 1 or 2 people instead of a group of 7 which may have made it think twice about charging.
Other than that I don’t see how an adult would have helped.
Given the number of kids that were injured, I'd say they panicked. I think an adult would have gotten the other kids to retreat and climb trees and then used pepper spray to try and get the griz to back off. I don't think anything could have been done for the first victim but the fact that six got injured indicates they didn't seek safety in trees.