Whole blood is allowed to be put back into the body if it's only in small quantities that have been treated with radioactive markers.
So that when you get a nuke CT scan they can trace the blood flow. The WT says "some brothers" may not object in their consciences to such treatments.
So if whole blood is ok to be put back into the body after having been taken out and sent to the lab for nuking then reintroducing it into the body... How can it be different than whole blood transfusions?
Sounds to me like the Passing Governing body had been growing older and in need of medical treatments that needed such therapies and so the rules were changed. Now that the GB is not so much made up of folks in their 80s and 90s there is likely little empathy for those who might need blood treatments, until that is in a couple or more decades the current GB feels the need for such therapies themselves.