I probably wouldn't have called it anything else - it's a punchy word for a title that means something to the wider audience even if technically, it wasn't apostacy as we understand it.
Overall, it's a fantastic movie for catching the feeling of being a JW and people's mindset as they make decisions that impact their own lives and others.
It's actually a good, powerful, gripping and moving movie in it's own right and worth a watch regardless of the JW subject matter.