Let me first say that I commend this individual for going out and researching his brother's illness on his own. It is truly a dedicated family member to go to such lengths as to attempt to understand things to the level of physicians, and further to attempt to convince physicians of the "correct" answer.
The first and most practical issue I wish I had seen was a GP coordinating the care. In general, the overall goal is to have a single physician be "your" physician, who can coordinate the care among specialists. The general idea is to decrease the amount of repeated and unnecessary interventions by making sure everything is being done in a medically appropriate way; additionally, it provides the patient an opportunity to explain to a single provider his or her desires in seeking treatment, and to make sure that the specialists are informed of such goals as well.
However, he demonstrates a number a poor understanding of physician training and the role of the physician in today's society. First, on the issue of training: he seems to believe that all physicians graduate medical school and start practicing as full-fledged physicians. Rarely is that the case these days, as a residency is required in all or at least most specialties in order to qualify for sitting for the boards (the benefit is not only the additional training, but then insurance companies will actually pay for your work).
Lastly, on the role of physicians: While we've come a long way in the millennia since hippocrates, physicians do not know everything. They don't have every answer to every question, and they don't know the answer to your exact problem either. We still "practice" medicine, because we can't predict with complete certainty the outcome of every single case. At best, we can use intuition from experience and education, and science of the community to make our best assumptions. But medical providers will always be wrong, some percentage of the time.