RE: SHOULD DOCTORS HELP THEIR PATIENTS COMMIT SUICIDE?
Well, like I said, consent is the key to a universal ethic, or moral standard. Consent derives from bodily ownership, which is exhibited by a person acting under their own volition. This is an a priori fact; attempting to argue that people don't have exclusive control of their bodies requires one to exercise exclusive control of their body to do so, resulting in a performative contradiction.
So since each individual exhibits bodily ownership, and this is true for all individuals, then any moral conditions derived from this axiom is necessarily true for all individuals. Since the ability to exclude necessarily follows from having exclusive ownership, every individual has the ability to consent to any given action involving them. Violating that consent is never preferable, as consent demonstrates preference for a particular act; if an act was preferable, an individual would consent. Therefore, having one's consent violated is always undesirable, or wrong, to the individual whose consent is being violated.
All that to say: you cannot consent to having your consent violated, which makes having your consent violated wrong in all cases. Since this is the case for all individuals, being derived from an a priori truth, morality is not subjective in at least this case. Therefore, morality is not completely subjective, nor can it be.
But if the objective morality you just described is just the morality of the individual, doesn't that make it automatically subjective? If for example a murderer doesn't want to have his bodily ownership violated and doesn't consent to be taken to prison, does that make his arrest undesirable and wrong? And if it makes it undesirable and wrong only according to him but not to everyone else, doesn't that just make his morality subjective?
Normally, yes, but this is always the case for all individuals. That takes it out of the realm of subjectivity, as it is always the case when discussing individual human beings. The fact that a murderer doesn't want his consent violated and considers it wrong illustrates that point; no individual can consent to having their consent violated.
However, one cannot simultaneously violate an ethic and appeal to that same ethic in one's defense, which is why a murderer has no grounds to protest being arrested for his crime. That's a separate axiom from what we were discussing, but it does apply here as well.
Like I said, this actually strengthens your case, as there is no morally consistent way in which assisted suicide could be immoral.