People have also died from BT and only known pathogens can be tested for in blood. I remember when the AIDS epidemic, everyone that ever received a BT was going around like a nervous wreck.
Even the WT does not claim that the bad consequences of the unsafe use of blood is a justification for their interpretation of the biblical texts.
Surgeons take calculated risks every time they operate, with the risk factors escalating with severity of the condition, level of medical urgency, age and physical state of the patient on so on. Generally they do their best to inform the patient before hand and allow the patient to make educated choices. Sometimes they perform operations in far more risky situations than others (to use an extreme example; the difference between treating a soldier with severe blast injuries in a field hospital v. elective cosmetic surgery in a private facility).
The point is that with blood the risks generally are far outweighed by the benefits, especially when considered in emergency medical situations.
I would agree however that sometimes there is some pretty emotive language used in the argument and, whilst understandable, I think the subject is served best when treated simply on the facts.