There is no good answer for this one. I've seen baloney posturing on other sites. Let's try to avoid that as for rational discussion.
1. Take a shot / hit the kid
2. Jump in (if you could get in vs. the barrier), break a leg
3. Can't live with yourself - a. get therapy or b. can your family get along without you?
4. Go H2H with a wild dog pack because you can do XYZ becauses dogs are ABC - or they eat you also.
5. The mother was stupid - not relevant to us.
I think this was just very quick horror and speculation about what one would do is hard to verify. Maybe it makes us feel good to think we could stop the horror. We don't want to admit to being helpless. We just don't know if any action would have worked and thus be worth the risk to you. Easy to say you don't care about that on the forum.