You just don`t get it, do you! You say:
The date 539 is considered by the celebrated WT scholars to be a pivotal date for the purposes of constructing a chronology for the biblical period
Yes, and that is where they went wrong! They (the "celebrated WT scholars", lol) do consider 539 to be a "pivotal date", but they never should have done that! Do you have to be spoonfed? The date 539 is also a derived date, derived from a chronology in which the "pivotal dates" are from the years around 600, especially the date for the capture of Jerusalem in 597 (10 years after it, according to the "celebrated WT scholars" say that it was destroyed). Such as dr.Freedmans reply to the WTS after they again misquoted him:
This is one of the best-known periods of the ancient world, and we can be very sure that the dates are correct to within a year or so, and many of the dates are accurate to the day and month. There is therefore absolutely no warrant for the comments or judgments made by the Watch Tower Society based on a statement about our uncertainty. What I had specifically in mind was the disagreement among scholars as to whether the fall of Jerusalem should be dated in 587 or 586. Eminent scholars disagree on this point, and unfortunately we do not have the Babylonian chronicle for this episode as we do for the capture of Jerusalem in 597 (that date is now fixed exactly). But it is only a debate about one year at most (587 or 586), so it would have no bearing upon the views of the Jehovah's Witnesses who apparently want to rewrite the whole history of the time and change the dates rather dramatically. There is no warrant whatever for that.
And so, the dates of 539 and 537 (or maybe...538 ) are both derived dates, derived from other (earlier) events in Babylonian history. But still, you insist on using the derived date to go back and change the "pivotal date" that you used to arrive at the derived date! And while doing it, you simply don`t understand that this also destroys the derived date...
This is not so much about history anymore, Scholar, no matter how much you try to hide the forrest behind the trees. This is about pure, mathematical logic. Not even Yahweh could make 2 pluss 2 = 5.
Of course, you can try to prove me wrong. Provide us all with an astronomical tablet that (by itself) sets the date for the release/return of the captives to 539/537. That would make the date pivotal.