An objective determination of the liklihood of critical confusion is very persuasive. I don't know what the result would be, one might be surprised and find that most readers "get it right," as the model; and don't "get it wrong" with phrase 2 reversed. But my spidey sense says that either version will have about the same rate of critical confusion.
I do think that the statute needs to at minimum be revised to improve punctuation and mandate formatting. I don't know why the web site shows everything centered--that's positively goofy. But in this particular case, the sentence as marked reads:
I direct that the application of life-sustaining procedures to my body (check the option desired): (X) including nourishment and hydration.There is nothing in the document itself that would indicate that one should consider the second half of the third box (which isn't checked) to be part of Ms. Mae's selection. To be sure, such a reading isn't entirely grammatical, but even the model language in its normal interpretation would be rendered ungrammatical by the stupid colon before the list.