BTW, the blog post above is adapted from actual CMS guidance. So while there may be someone misinterpreting the new rules, it does not appear that CMS has changed the actual ability for doctors to make a hospice-eligible prognosis, only that they are required to clarify the diagnoses to better ensure that the patients are being treated properly in hospice for their conditions AND that if they are still alive after the first six months, there are clinical diagnoses that can be used to identify their ongoing status.
Malnutrition is an acceptable principal diagnosis, yes. He doesn’t have malnutrition. He’s eating as many calories as he should and while he’s dropped a lot of weight without intent (failure to thrive), he’s not clinically malnourished. Hypertension and cancer that isn’t very advanced aren’t, according to his doctor, appropriate hospice diagnoses because they are not causing his 6 month prognosis.
Basically, they want ti know what’s causing the failure to thrive. If the answer is, “we don’t know,” there’s nothing to put down for a principal diagnosis.
What you are saying does not agree with the CMS guidance. Again, they may be running up against someone who is misinterpreting the rules. That absolutely happens. But the guidance is clear.
[bolding mine]
I know this was serious, and I’m really really sorry. But my mental picture of your ex feverishly rolling dough while muttering at the oven timer has me laughing so hard I almost choked. 
I’ll be serious now. I promise.