Well, that paper leaves a lot to be desired. It assumes a particular definition of death that it explicitly states it's not going to argue for, equates death of a person with biological death without justification, and then expounds considerably upon what remains, when what remains is completely not the issue.

However, it does illustrate that some people do not consider brain-dead people to be dead people. So, yes, point taken.

Persistent vegetative state is complicated medically because we don't have good ways to determine whether the patient is conscious or sentient. Especially since we've now, belatedly, realized that there are things like locked-in syndrome. So I'm not sure that PVS is a meaningful counterexample either; it seems to me that the uncertainty about cognitive capacity is almost all of the debate there (aside from objections on religious principle alone, or on gut instinct: this looks like a person to me so I will treat them as such).

Regarding analogies, well, yes, I agree that they're always fraught. When you have sufficient similarities such that some of the primary concerns are the same, then analogies can still be useful, but the case of embryos vis a vis consciousness is so different from almost everything else that I can't think of a useful analogy.

Anyway, thanks for considering my comments!