The point is to simplify the timeline. If I prevent him from dying, then the events of FNaF might never happen. Then we just have to keep his dad from murdering people.
I would run in there, hit Michael with an axe, hit Fredbear so hard his jaw falls off, rescue Evan, shoot Michael in the skull with a Glock-17 while he's lying there, crying, and then go back to my time.