For lurkers, FTD subscribes to a 19th century extremist Lutheran Old Testament scholar who denies Septuagint.
FTD claims that LXX was retro-written by Greek Christians to make it "fit" the New Testament.
In other words, FTD says that Septuagint is, to put it simply, a fraud. You may want to take that in to consideration when discussing this with this individual.
And do you have any manuscript proof that an B.C. LXX actually existed.
All you do have is some BC fragments of the Torah, which were likely Targums, not part of any complete LXX
Christ and the Apostles never quoted from any LXX or the Apocrypha.
What you are perpetuating is the myth of the B.C. LXX.
Dr. F. F. Bruce correctly points out that, strictly speaking, the LXX deals only with the Law and not the whole Old Testament. Bruce writes, “ The Jews might have gone on at a later time to authorize a standard text of the rest of the Septuagint, but . . . lost interest in the Septuagint altogether. With but few exceptions, every manuscript of the Septuagint which has come down to our day was copied and preserved in Christian, not Jewish, circles.” (The Books and the Parchments, p.150). This is important to note because the manuscripts which consist of our LXX today date to the third century AD. Although there are fragments which pre-date Christianity and some of the Hebrew DSS agree with the LXX, the majority of manuscripts we have of the LXX date well into the Christian era. And, not all of these agree.
http://www.purewords.org/kjb1611/html/lesson08.htm