The heck with "authorizing" the provision of nutrition and hydration. She is ORDERING IT. She is DEMANDING it.
Also, Ken's use of "in a coma" may have been colloquial or lazy talk. It may be that his mom was sedated and not terribly responsive. The medical treatment that permits the dissection to heal likely requires a person to be fairly still. And/or, Ken's mom may not have been "caught" at the same time in the progression of the dissection.
It's too bad that Gaddy is such a pucker-butt that she won't communicate.
Looks like you and I agree on Mae's intent and as you said, ORDERED it to be done if she is in EITHER state; coma or PVS. Any attempt to ignore her request is (IMO)attempted, 1st degree murder, with malice and forethought!
As to the loving and so caring G-daughter, the truth has no reason to hide. Those that won't step-up are afraid and have no defense. If she doesn't provide her "truthful" side of this issue, it will be perceived as falsehood on her part and further validate the claims of Ken, etc.
Personally, if I were she, and I was telling the truth, I'd be right there in their face backing up my statements!