Arguments for anti-presentism?

Bill has been discussing David Benatar's The Human Predicament. Benatar introduces what he calls the Existence Requirement,

(ER) In order for something to be bad for somebody, that person must exist at the time it is bad for him.

Many people find this self-evident. Bill argues here that the reason for this is a tacit commitment to presentism. Bill explains presentism via a somewhat murky notion of 'existence simpliciter', but I think the gist is captured by the following,

Consider Tom Petty who died recently. On mortalism, he no longer exists. On presentism, what no longer exists (i.e., what existed but does not now exist) does not exist at all. So on presentism, Petty does not exist at all. If so, dead Petty cannot be subject to harms or deprivations.

So if we have grounds for rejecting presentism, we can also reject Benatar's Existence Requirement.  But why would we want to say that ceasing to exist does not imply ceasing to exist at all?  What residuum of existence remains after something has ceased to exist?  Bill says,

We don't want to say that a dead man becomes nothing after death since he remains a particular, completely determinate, dead man distinct from others. If the dead become nothing after death then all the dead would be the same. If your dead father and your dead mother are both nothing, then there is nothing to distinguish them.

It's difficult to know what to make of this.  My guess is that Bill is conflating a thing with the idea of a thing.  First, 'particular' and 'completely determinate' do not denote properties of  concrete objects like men.  One can contrast 'I have in mind a particular man' with 'I have in mind a man' but 'particular' here qualifies not 'man' but rather the way of having in mind.  'Completely determinate' functions in a similar way.  What would 'partially determinate man' denote?  A partially determinate idea of a man makes sense, however;  we know some of his properties but not others.  Second, 'dead' is an alienating adjective.  If a man is a living thing and 'dead' means non-living then a 'dead man' is a somewhat contradictory conception.  Better to think of 'is dead' as 'has died'.  A dead man is one who has passed through that final event that all living things inevitably come to, and has ceased to be.  Third, to speak of 'becoming nothing' on death is misleading.  Death is the end of all becoming.  One has finally begone, as it were. It's not that the dead lack something to distinguish them. Rather, they are not there to be distinguished one from another.  But this is not to say that my parents were indistinguishable as objects.  Nor is it to say that my thoughts about my parents are now indistinguishable.  Surely I can say, My mother was short and my father was tall. 

Nor do we want to say that a person who dies goes from being actual to being merely possible. There is clearly a distinction between an actual past individual and a merely possible past individual.  Schopenhauer is an actual past individual; his only son Willy is a merely possible past individual

Once again I'm afraid I can't regard 'being actual' and 'being merely possible' as denoting properties of individuals. How these predications are to be understood is not an easy question.  Suffice it to say that there is clearly a problem with  'Schopenhauer's only son Willy' when the philosopher's only child was a daughter.

On the 'growing block' theory, dead Petty exists. (This is obviously not a present-tensed use of 'exists.') He does not exist at present, but he exists in the sense that he belongs to the actual world.  Once actual, always actual. Is this wholly clear? No, but it is tolerably clear and plausible. After all, we are making singular reference to Petty, a concrete actual individual, as we speak, and this is a good reason to hold that he exists, not at present of course, but simpliciter.

The 'growing block' theory sounds like a kind of four-dimensionalism deriving from the physicist's notion of spacetime as a four-dimensional manifold.  We trace the world-lines of the particles that were ever part of Petty and we find that they form a densely packed blob within a certain spacetime region.  We are tempted to identify the contents of this region with Petty himself.  If we think of the ensemble of worldlines of all material particles as the actual world itself, then yes, the Petty blob seems indeed to belong to the actual world.  But this is a mistake.  The worldline of a particle represents not so much the particle itself but rather its history.  Likewise the blob we take to be Petty represents his biography, in mind-numbing detail.  We are confusing a thing with the life it lived.  Of course Petty belonged to the world---I don't see quite what 'actual' adds here---it's just that he does not belong to it any more.  Perhaps Bill is emphasising that Petty was a real man, not, say, a character in a fiction like Spinal Tap.  There is more than a hint here that Bill is appealing to a theory of direct reference.  Petty has to exist in order that we may refer to him.

In the article, Fiction and Alienans Adjectives, I discuss this and related matters with Bill.