I believe the idea is to prevent gnolls from killing them without protection?There's no reason to run toward the prisoners until the gnolls are all dead. It's not like the prisoners will be able to run away.
Why would they do that? For all they know we are just highwaymen trying to kill them. Taking actions that don't save their own lives in the event we are interested in the prisoners makes no sense. I don't think Gnolls are known for their dedication to "the cause" above their dedication to "staying alive".I believe the idea is to prevent gnolls from killing them without protection?