If we exist in a block universe, then all time-travel effects are "already" baked in. Just because something's path through the block isn't always "forward" doesn't mean it can change its path, or anything else's.
In a growing block universe, I think time travel would be impossible, but I also think that the growing block universe theory is cope.
In a growing block universe, I think time travel would be impossible, but I also think that the growing block universe theory is cope.