it is considered historically reliable
That doesn’t sound very scientific if the assumed date has any bearing on the accuracy of the results.
Also, if I read the article correctly, it describes the resulting data as probable and not as a measurement with the tolerance.
Off the top of my head, I’m not sure ( I didn’t check) I think that 539 is the standing WT also uses to establish the fulfillment of the Messianic prophecy in Daniel 9 of Jesus in the 1st Century.
If 586 does not line up with Christian interpretation of Daniel 9, there is a problem.