Good post! I too am interested in the God and time issue, although I'm much closer to Craig's view.
I think your characterization of (1a) is not accurate to Craig's (and other's) arguments. The point in bringing up tensed facts is not to say "God knows temporal things; therefore God must know them temporally." Rather, it would be something like this:
(1a*) Tensed facts (if they exist) can only be known by a being in time.
The point is that if certain facts are tensed, and if God knows them (i.e., if God is omniscient), then God would have to be in time to know them.
As I see it, the debate turns on these questions: (1) Are there such things as "tensed facts"? (2) Is it possible to translate all facts into "timeless" propositions? I am convinced that certain facts have a tensed aspect that cannot be eliminated. Moreover, since I am convinced that God knows all facts, I believe he exists temporally.
I agree with the (1) and (2) as characterizations of the way the debate actually tends to go; I stand firm by my position that they are irrelevant to the question of consistency, though. I see the same sorts of problems arising with (1a*) that arise with (1a): we have no reason to believe it to be true. We cannot know it simply by induction from cases we know; so there would have to be some sort of necessary connection between tensed facts and knowers in time. But we would need to know exactly what it is about tensed facts that makes them such that whoever knows them must be in time; and there is, as far as I can see, no plausible account of this. This issue is not whether we can translate all facts into timeless propositions; the only reason we would think this relevant to the question is if we already assumed that a nontemporal being could not know tensed facts precisely as tensed, which would be what is at issue. Craig tends to assume that (1a*) is a necessary truth; but, if so, it is not an obvious necessary truth: the denial of it has been the dominant position of philosophical theologians through the centuries. So there needs to be some sort of analysis that would require us to say that knowing facts that are tensed necessarily entails that the one who knows them be temporal. (And this, note, is very much a family relation of (1a).) Further, we need such an analysis because similar patterns of arguments do not appear to work for other sorts of facts; so we need to know anyway why tense is so unique (see here for discussion of a related issue).
The reason I formulated (1a) the way I did is that there are several different variations of the same type of inference proposed by, e.g., open theists or process theists; all of which face similar problems. (1a) was the most general formulation I could come up with at 3 a.m. to describe the entire group; it's possible that there's a better formulation somewhere. So, while I'm less cranky at the moment, I hold fast to my basic positions: the participants in the debate are treading dangerously close to claiming that they know what God's experiences are like; the issue of whether there are tensed facts is largely irrelevant to the question of divine timelessness, because we have no reason to believe the claims that the existence of tensed facts would require that an omniscient being be temporal; while it's an interesting question, nothing actually turns on whether we can translate all tense facts completely into tenseless propositions; and so forth. At least, there's a lot more work to make the inference work than most people admit.