"Facet", I think I know you in real life!
Anyway, if it is who I think it is, I will be attending your seminar next Wednesday to find out what you have to say on this exact topic, for which I saw the flyer today. "Graduate student"? :)
The truth is, Facet, it is extremely unlikely for a JW to not have filled out the blood card completely. These cards are filled out under extreme pressure (in my opinion) once a year after a sermon on the topic. Then there are specific church leaders ("elders") assigned to different members of the congregations to make sure each one has their card filled out completely. I just don't think this scenario would come up very often given the circumstances.