Goodman defines something as "grue" if it is first observed before Jan1, 2025 (say) and is green, or is first observed after Jan 1, 2025 and is blue. He uses this to make a point about induction: any evidence we cite as evidence for the proposition "all emeralds are green" is also evidence for the proposition "all emeralds are grue." Thus, the grue problem casts doubt on the rationality of inductive conclusions.
So we see that Goodman's point was about induction, not indeterminacy. But this is really unimportant for Ross's argument, because Ross doesn't actually use the grue argument in any essential way. Rather, he either cites grue as an example of the problem of limited data, or as an analogy to Kripke's quaddition argument. For instance, Ross writes:
A decisive reason why a physical process cannot be determinate among incompossible abstract functions is "amplified grueness": a physical process, however short or long, however few or many outputs, is compatible with counterfactually opposed predicates; even the entire cosmos is. Since such predicates can name functions from "input to output" for every change, any physical process is indeterminate among opposed functions. This is like the projection of a curve from a finite sample of points: any choice has an incompatible competitor.But the problem of limited data, as we have seen, is irrelevant for the indeterminacy question. So the grue point devolves onto the Kripke/quaddition point, which I will consider next.