Good scholars, as opposed to "celebrated Watchtower scholars", know how to argue a case with facts and always fully explain their reasoning to their readers. On the subject of the date of return of the Jews to Jerusalem, the Watchtower Society has only given speculation. Its argument boils down to a mere "in view of the Bible record" but it gives no actual arguments as to why that Bible record supports its claim. The clearest words the Society has written on this subject are found in the Insight book, Vol. 1, p. 568, under the subject "Cyrus". Note the complete lack of supporting evidence for the conclusion, and how the writer turns pure speculation into a supposedly solid conclusion:
Cyrus’ Decree for the Return of the Exiles. By his decreeing the end of the Jewish exile, Cyrus fulfilled his commission as Jehovah’s ‘anointed shepherd’ for Israel. (2Ch 36:22, 23; Ezr 1:1-4) The proclamation was made "in the first year of Cyrus the king of Persia," meaning his first year as ruler toward conquered Babylon. The Bible record at Daniel 9:1 refers to "the first year of Darius," and this may have intervened between the fall of Babylon and "the first year of Cyrus" over Babylon. If it did, this would mean that the writer was perhaps viewing Cyrus’ first year as having begun late in the year 538 B.C.E. However, if Darius’ rule over Babylon were to be viewed as that of a viceroy, so that his reign ran concurrent with that of Cyrus, Babylonian custom would place Cyrus’ first regnal year as running from Nisan of 538 to Nisan of 537 B.C.E.
In view of the Bible record, Cyrus’ decree freeing the Jews to return to Jerusalem likely was made late in the year 538 or early in 537 B.C.E.
In contrast, note how scholar T. C. Mitchell, writing in The Cambridge Ancient History (Second Edition, Vol. III, Part 2, "The Assyrian and Babylonian Empires and other States of the Near East, from the Eighth to the Sixth Centuries B.C." Ed. by John Boardman et al., Cambridge University Press, 1991, pp. 432 etc), clearly explains his reasoning and presents various facts to support it:
It is a reasonable hypothesis . . . that work was begun on the Temple site under the direction of Sheshbazzar as soon as the returning exiles reached Jerusalem, probably in 538 since, though Cyrus' first year ran from spring 538 to spring 537, he had taken Babylon in October 539, and it is unlikely that he would have allowed any great time to elapse before he issued the decreee. According to the Book of Ezra, Zerubbabel, Joshua the high priest, and others assembled in Jerusalem in the seventh month. There they built an altar and re-established the giving of burnt-offerings on it, celebrating in particular the observances of the festival of Succoth (Booths or Tabernacles) (Ezra 3:1-6; I Esdras 5:46-52). In the Jewish calendar, Succoth was kept in the seventh month, Tishri, to mark the time of harvest (Lev. 23:33-6; Deut. 6:13-15). This strongly suggests that the `seventh month' in which Zerubbabel built the altar was Tishri in 538, rather than simply the seventh month after the return, and that the end of the summer, when the people had been able to collect some kind of harvest from the untended plants of many decades and perhaps from those inadequately tended by those who had remained in the land, was a time when the distractions of self-interest relaxed and thoughts could turn again to religious matters. It seems that the people also now made financial contributions towards the bringing of cedar wood from Lebanon (Ezra 3:7; I Esdras 5:53). This transaction presumably took several months, for Zerubbabel is said to have begun organizing the building operations in the spring of the following year (second month of the second year of the return), at which time the foundation of the Temple was laid to the sound of music and song (Ezra 3:8-11; I Esdras 5:54-9). This reconstruction would therefore see an initial symbolic foundation-laying by Sheshbazzar in the spring or early summer of 538, followed by a failure on his part to inspire the people to continue; then a renewal of the operation under Zerubbabel some four or five months later, with the building of the altar in the autumn; and, finally, the laying of the foundations in the spring of the following year, 537, after a winter during which arrangements were made for the supply of building materials. This event would have taken place almost fifty years after the destruction of the Temple by Nebuchadrezzar, and it is recorded that many of those present wept because they had seen the first Temple (Ezra 3:12-13; I Esdras 5:60-2), a strong indication that the `second year' in question (Ezra 3:8; I Esdras 5:54) was the second year after the return in 538, and not after a second return in 520 by which time it is unlikely that `many' would have remembered the first Temple.
The last point that Mitchell makes is telling as far as the length of the captivity is concerned. Since many Jews remembered the first temple, it is far more likely that many of them were in captivity for only 50 years rather than 70. At that time the average life span was significantly lower than the required minimum of about 80 years that would be necessary for "many" to remember the temple, but if the "many" were only about 60 years old and up, there is no problem. It is little details like this that Watchtower writer fail to account for, in addition to the bigger issues which they generally deliberately obscure and misrepresent.