Flight crew are not in a position the make a call on what is a serious injury and what is not
The flight crew would not have made the medical decision. It would have been discussed with a "medlink" doctor, via Sat Phone.
Medlink and those Doctors are paid by BA to make medical decisions. 24/7.
Having made a decision it would then be constantly reviewed with the Doctors, via Sat Phone.
Almost certainly there would be someone on board with medical qualifications, and they tend to act as a go between. Medlink ask the question, you ask the doctor on board the question, you relay the answer.
beernice: This is another example of the ignorant condemning BA at every opportunity.