Devil's advocate for why ontology is meaningless and vacuous.

[Excited Penguin]

Devil's advocating for some premises:

Premise 1. Subjectivity is ontologically objectively existent.

Premise 2. Moral values are purely and wholely epistemlogically subjective.

Premise 3. Those wholly epistemolgically subjective moral values reside ontologically objectively existent within all human brains.

Premise 4.  Those ontologically objectively existent moral values residing in human brains are just as capable of disageeing with one another as if they were not ontologically objective.

Premise 5. Ontological objectivity is both entirely meaningless and valueless and there is no difference whatsoever between ontologically objective moral values and fully subjective moral values.

In summary I'd conclude that ontology is meaningless. 'Being' is indefinable and therefore no different to 'nothingness' because nothingness can't be anything anyway because it's nothing. There is no nothing.

I'm doubtful of premise 2, absent of clarification.  There's a lot to unpack in your usage of the words "moral values" and "purely and wholly epistemologically subjective."  I would argue that, in my understanding of "moral values," that is, how one ought to live in relation to others, the maximization of the total happiness is an ideal that is intrinsically valuable, or good, and moreover, entails an epistemologically objective truth about the world insofar as its broader principles are apprehended and confirmed by anyone capable of rationality.  It is only subjective when applied to particular situations.  

I don't see how premise 4 can be true.  People disagree because knowledge is derived from subjective experience, the multiplicity of which perceives the world from a variety of vantage points, both inwardly per one's physical composition and due to the surrounding circumstances, yet this doesn't render the world as if nothing were "ontologically objective."  I assume you believe that we can speak objectively with regards to ideas about material facts.  Why then do you assume otherwise with regards to ideas about ideas, which are what moral values amount to, more or less?

Thus, premise 5 doesn't follow.  There surely is a difference between truth and opinion; "chocolate is relatively better than vanilla" is an opinion that expresses a subjective fact about a particular consciousness; "pleasure is intrinsically better than pain" is a truth that expresses an objective fact about general consciousness.

Being is not nothingness, and nothingness is not meaningless, at least taken relatively.  So, no, ontology is not meaningless.  The problem is rather that your premises make all sorts of ontological assumptions about the reality or actuality of ideas as opposed to material objects, which is ironic given that it is itself an idea that purports to be true... But what is the ontology of truth, and why grant it, but reject moral values?

Hey, dude, where you been at?