Look, the issue is not really this particular case, even a hypothetical. The real issue is the precedent state forced "medical" care presents. Are there some people out there who, for whatever reason good or bad, choose not to send their kids to the hospital? Yep. Just like there are some parents who choose not to send their kids to the state run school.
If we take a hypothetical like this, and react in with this "think of the children" nonsense please pause for a minute and actually think of the children. If we allow the state to mandate a child is taken for treatment for cancer, perhaps a good thing; tell me then how, many kids will be ordered to receive mandatory treatment for more benign, even relative, things like ADD or depression?
In the scheme of things, the number of parents that would endanger their child over their religious beliefs is very small; but the number of kids the state would inevitably order to treatment would be invariably large, and most of the cases I guarantee would be things like ADD, depression, ADHD and other psychological issues that our truly relative. Don't leave out flu shots, mandatory vaccinations, and this list could go on and on and on.
"Big Pharma... they care about the kids." gimme a fuckin break
If we are to live in a land ruled by law, then we need to be very careful in the precedents we set. If we are incapable of setting precedents carefully, than Murray Rothbard is completely right in abolishing the state. It is often evil wins us over with trifles of good.