Only the eternalist will accept it. Savitt says that this doesn't yet give us a satisfactory way of drawing the distinction. He says that since it was correct to assert Newton exists now, it was correct to assert Newton EXISTS, as whatever exists EXISTS. And since EXISTS is "non-indexical" (truth of 'x EXISTS' does not depend on a moment of evaluation), it is now correct to say Newton EXISTS, even for the presentist. But why would the presentist accept a non-indexical reading of EXISTS?
Quantifiers like 'There are' or 'Every' have a domain they range over. When we say 'Everything is material' we quantify over certain things. We can read that sentence as true even if there are non-material things like abstract objects (e.g. numbers) since often context restricts the domain of quantification. In this case the sentence might be true because it means, besides abstract objects, everything is material (e.g. there are no souls). If we understand quantification unrestrictedly, then we have a way of understanding which things we are ontologically committed to--which things exist in the most general sense. E.g. if we can truly say that there is something that crossed the Rubicon and was called 'Caesar', we are thereby committed to the existence of Caesar. The idea is that we can do this without worrying about which sense or tense 'exists' has. Savitt is not convinced, however, since he thinks that when we specify unambiguously what the domain of unrestricted quantification is, we will have to do so by saying which things exist.
Eternalists are supposed to grant
(6) There is an x such that was (x = Newton),and presentist's not. But how are we to read the the first 'is'? If it is present-tensed, then eteranlsits will deny it. If it is the tenseless IS, then Savitt claims we can't coherently interpret (6), for was is supposed to have an effect on the truth-value of sentences it attaches to (it is "indexical"), while IS is non-indexical. However, I don't understand why this would prohibit a coherent reading of (6). The fact that was is non-indexical does not mean that it always has an effect on the truth-value of sentences it attaches to. It does not, e.g., have any effect on the truth-value assigned to 'On 4 Novemeber, 2008, Obama was elected president' since the proposition to which it appends is true at all times. Moreover, the eternalist does not need to even put the temporal operator in (6) since they also accept, where the presentist doesn't,
(6') There is an x such that x = Newton.For these reasons I don't think Savitt's argument quite succeeds.
He says relative to some background spacetime theory. Once we lay down that background theory, we can say what presentism amounts to. Savitt provides one way of doing this on the assumption that spacetime is Galilean. However, it seems to me to assume an objective eternalist picture, and then views presentism as a view about perspective. As such, I don't see that any thoroughgoing presentist would accept it.
It is that presentism and eternalism are compatible. Given the Dummett quote, he appears to view the distinction as one concerning perspective. The presentist takes an internalist perspective on time, seeing only what they have immediate internal access to--what occurs now--whereas the eternalist has an externalist perspective on time, viewing the whole manifold at once, looking at the presentists situated somewhere in the now.
In the end, it is clear that Savitt's view is eternalist. Presentism concerns not ontology, but instead perspective. If they are both true, then past objects do exist since they are elements of G (barring footnote 38), even if we have no causal access to or influence over them.