No. The eight other bears didn’t kill Brian Matayoshi (the first person killed).
The same evidence that linked the other eight bears to Wallace’s dead body is the same evidence that linked this particular sow to Wallace’s dead body - DNA from scat that shows she (and eight other bears) fed on his body.
There was no evidence given that would indicate this sow as more likely than any of the others to be the killer until she was linked to a second mauling death.
So do you suggest that if a hiker is killed by a bear and they show that nine bears fed on his body - that all nine bears should be killed?