The reason that the medics etc are so exercised I think is because of the way that this was done. If the parents had discussed with the doctors their wish to take the child elsewhere, then proper plans could have been made to connect up with another hospital abroad, to make sure he had batteries for his feeding device, to send over the medical history etc.
Instead they just "did a moonight flit" which raises concerns all round.
He is not the property of the doctors, but they do have a duty to make sure he gets proper care and the chance to live (if that is possible).
I can understand that the parents might have feared that he would be made a ward of court if they let the hospital know their plans and wishes, and it does sound as though they have other plans for this lad than medical opportunities to save his life.
It is a dilemma for the medics - their understanding of what is possible is better than the parents; but on the other hand the parents know their child best and may feel differently about treatment. It is always difficult when this happens, as religious beliefs may stand in the way of providing a minor (who cannot express his wishes well) a chance of life.
I wonder what we would be doing if we were in the medics' shoes?