I think he strikes a good point. There is a lot of theory as to the nature of time, and evidence has suggested that time isn't necessarily linear. Certainly, data suggests that time itself is subject to external factors, such as theories regarding time in relation to relativistic velocities and/or massive objects ie. black holes.
Despite this, our consciousness is limited to any given moment in time; the 'present.' We are able to recall things we have witnessed in the past in varying levels of detail, but we are still only actually aware (in terms of perception) of the present. Modelling time as a fourth dimension, we are said to be able to move freely on two axis, have limited mobility vertically, and move forward along the time axis in what is, ostensibly, a linear rate (1 second per second). Even that is questionable, as subjective perception of time varies from individual to individual, and indeed varies from point to point with any given individual.
If a hypothetical God is omnipotent and omniscient, wouldn't that by definition remove those restrictions from said entity? I would say that being able to actively perceive any given point in time (past, present, or future) would essentially be a requirement for true omniscience. By that same token, I would presume omnipotence would also imply no restrictions in terms of ability to freely "move" along the time axis as well.
Assuming time is linear, and progresses along a straight line, the argument is that free will does not exist because the outcome is predestined. Is that necessarily true though? Does an external 3rd party who already knows what you're going to decide before you decide it remove that choice from you? I suppose it depends on choice.
But what about the 'many worlds' model? The case where at instances where a choice is made, or there is a "random" chance of any given occurence, all of the possibilities occur, but in different universes (so to speak). In this case, I would presume that an omnipotent and omniscient being would be capable of perceiving all possible futures from any given point.
This kind of thing could be argued for years... your statements make presumptions regarding the nature of time that there isn't any hard data or evidence to back up. Not just that, but to assume that a theory is untrue when there is no evidence to either support or disprove it makes the presumption that all possible data on the matter is both available and correctly interpreted, which I see no evidence for, and in fact see a good deal of evidence to the contrary.
While on the God subject- that question "If God is all powerful, can he create a rock so massive that he cannot lift it" is a popular one for the less educated atheist philosopher. The answer is simple- yes. If said rock was massive enough that the center of gravity for the entire universe was contained within its mass, then it could not be "lifted" by definition.