Lol, that would be ...interesting... dialogue. I think it's fairly self-explanatory tbh, and Giles does say something along the lines of 'in this context, it means ie. when Dawn is dead.' And the term 'bloodflow' etc is still used (though I assume not by scientists) to described the flow or circulation of blood... I don't think in general that people are aware of the difference, and even if they were, they would also be aware that in the context of ancient ceremonies and ancient texts, blood ceasing to flow would mean lack of life.