In the simplest of terms, theory T is inconsistent with theory T* if the conjunction of T and T* entails everything in a classical logical system.

Since QM is inconsistent with GR, and since not every proposition is true, either QM or GR is, strictly speaking, false. Perhaps both are false.

The OP, Eliezer, must think that GR is false, since he's gone out and endorsed QM. This is not a good position to be in. More charitably, the OP has tried to endorse everything in QM that he thinks he needs for his argument, and he's asserted that all that requisite material will be retained in any future scientific theory.

The OP is then pleading that whatever physical theory turns out to be true will be sufficiently like QM that he's entitled to rely on QM in the ways he is. Call this quantum mechanical optimism or hopeful thinking. I don't see the argument here. Sorry.

He can conditionalize his claims. He can say things like, "If QM is true, then..." or "If the true physical theory preserves what there is in QM that I need for my argument, then..." But this isn't what he's doing.

And finally, even if the OP were to conditionalize, he'll still in hot water. Maybe the OP means by "physical nonsense" something like: contradicts claims that follow from QM. But he doesn't mean this. He's trotting in his own favorite little philosophical theory, without defense while pretending to rely upon good science (though he's in fact relying on very probably false science, since QM and GR can't both be true). This is evident when he writes: "The imaginary identity-tags that read "This is electron #234,567..." don't affect particle motions or anything else; they can be swapped without making a difference because they're epiphenomenal." Let's suppose that there are such particle-tags. Call them properties. And let's grant that they don't affect particle motion. Let's even grant that they're epiphenomenal. See how charitable I'm being to the OP?

Now obviously, it doesn't follow from QM that these epiphenomenal particle tags don't exist. The OP can beat his brain against the wall for the rest of his life and never manage to show it does so follow. Eliezer believes these particle tags don't exist, which is why he calls them imaginary, but he has not managed to produce one wit of evidence for that claim. I take it the OP would probably rely upon the following assumption: Nothing epiphenomenal exists. That's an interesting philosophical claim, and the OP can't pretend to defend it by giving us more very probably false physical theories. Nor does it follow from any physical theory the OP has mentioned so far.

When reading the OP, I am reminded of William Lane Craig's attempts to use The Big Bang to defend a central claim he needs for his Cosmological Argument: the universe had a beginning. Craig is in hot water here, for it does not follow from any of our best scientific theories, including all Big Bang Theories, that the universe had a beginning. Craig is using scientific dressing to peddle shoddy arguments that those unfamiliar with the science will be rhetorically overwhelmed by, and I don't see the difference between what he does and what the OP is doing.