"Cancer" Is a catch all used to describe many diseases. For some, chemo is ineffective, for others it is HIGHLY effective. The reason the "alternative" treatment is not offered in the US is probably because it is impossible to prove scientifically that it works. In this case, Hodgkin's disease, it is extremely effective.

The legal line is that the child is under 18, therefore a minor under his parents' care. They are required to ensure the welfare of the child. If their alternative medicine choice was prayer, would you support that? Somehow I doubt it, and the courts have also ruled that that is insufficient. If the Hoxley cure was indeed effective, the FDA would probably allow it.