I read on redstate that they made this choice after a us Doctor looked at the scans and records. I suspect this choice to let him pass was based on his opinion.
Yes. ANd if they had allowed that visit 6 months ago, EITHER the doctor would have found the same thing, in which case the parents would have known there was no chance and probably not spent the last 6 months in THAT hell, instead enjoying the time with their child before he was gone. OR he would have found the child still eligible for the treatment, in which case they would have had hope and a plan.
British law and medicine denied them either outcome, inflicting legalities on a personal decision. Shame.