It’s mild hyperbole. Strictly speaking, pounding the skull into the wall until they stop twitching would probably mean completely dead.
Blood chokes, that work to cut off the flow of blood to the brain instead of restricting the victim’s breathing are incredibly dangerous, to the point that brain damage or death are likely, to not completely guaranteed. So, without any hyperbole, it would be more accurate to say, “these are both very dangerous and can result in death.”
It also gets into the entire discussion about human beings as a whole. We are remarkably easy to break, but hard to kill. There are mountains of medical cases where someone suffered what should have been a fatal injury, only to survive. Grievous head wounds are an example of that.