Greer didn't just forbid artificial nutrtition and hydration, but natural nutrition and hydration as well. There is no legitimate rational basis for doing so. Even if oral feeding would have imposed a significant risk of aspiration and had only a small likelihood of success, that is no basis for forbidding it altogether. Note, btw, that a patient will "fail" a swallowing test if doctors feel there's any significant risk of aspiration, even if there is in fact a high likelihood of success.
Blame the legislature for writing crappy laws. They want you to blame judges, but I don't buy it, and I don't think you should either.