It is a clinical term, you are arguing over semantics. Cardiopulmonary death to be specific. My point is: no one knows, not you, not me, and not my dog.
I don't know what's behind a wall I'm sitting next to right now, but I'm reasonably sure there's a street. I'm also reasonably sure the comment about "you've been dead" is also a very accurate prediction.
That wall is concrete and material. Death is not so much. I am reasonably sure you can do that with great accuracy while still having zero idea what lies in wait for us after we die. A false equivalence.