Let's count how much evidence is deemed "useless."
The collective tradition that Ezra wrote the Pentateuch in the Persian period.
The collective tradition that the LXX was TRANSLATED by scribes in Alexandria and celebrated as a translation by generations of Alexandrian Jews with a festival down to the time of Philo
The Samaritan tradition of the LXX being from around 150 BCE.
Hecateos's testimony regarding Jewish practices from 300 BCE.
What is accepted as "convincing evidence."
Jewish scribes in Alexandria "worked on" the LXX
There are parallels with Berossos's Babyloniaca published by 278 BCE
There are vague similarities with Plato.
The fact the Library of Alexandria with Berrosos's Babyloniaca existed before the earliest fragment of the Pentateuch at Qumran (c 250 - 200 BCE) it "stands to reason" that "Samaritan and Jewish scribes" employed Greek texts in the library "collaborating" to "invent" the Pentateuch by about 270 BCE.
However some obvious difficulties.
1. Cherry picking of evidence - the Letter of Aristeas.
You accept its dating of the translation of the LXX under Ptolemy II. Nevertheless the same text makes explicit the Seventy worked on a translation not an "invention" of the Pentateuch. The Pentateuch is assumed by Aristeas to be a pre-existent Hebrew text already established elsewhere. There is no other source other than Aristeas which dates the Library to Ptolemy II. Hard to see why evidence that favors your proposition is "accepted" while evidence from the same source which disproves your thesis is rejected.
Dating of the LXX.
Gmirkin's dating of the LXX to 272 - 273 BCE is a lot earlier than most scholars.
"The Septuagint, the oldest translation of the Old Testament by the Jews into Greek (about 250 B.C.E.), was written in Alexandria." Myrto Theocharous.
2. the Samaritan tradition suggests the latest date possible which Hjelm does not reject out of hand and seems to promote.
3. as a result the dating of the LXX by many, many scholars is contemporary with or later than the earliest Qumran fragments (c. 250 BCE).
"Regarding the date of the translation, the Letter of Aristeas could be transmitting accurate information, though a date to the reign of Ptolemy III Euergetes I (246–222/221 BCE) or Ptolemy IV Philopator I (222/221–204 BCE) cannot be fully excluded." Luke Neubert
"One of the major intersections between Hebrew and Western orthography occurred when the Hebrew bible was translated into the Greek Septuagint (250 B.C.E.—150 B.C.E.?)" Robert J. Scholes
The arguments for the dating of the Septuagint to 250 BCE are not even that solid.
https://books.google.com/books?id=_g_UA ... nt&f=false It could be as late as 150 BCE. Like I said, you take the earliest date for the LXX, the Library of Alexandria and the presence of Berossos there and the latest possible date for the Hebrew texts. If you do all that you attain a holocaust of Hebrew literature. Like I said you're not killing Jewish people, just Jewish books. If it makes you happy so be it.