How do you know it is a latter day addition? You don't. We don't have the original autographs. As I stated before, just because a particular manuscript is older doesn't mean it is better. Lots of heretics took their crack at writing books and tinkering with Scripture.
The textual critics ASSUME that it was a latter day addition because in some manuscripts it isn't found in there. In others (quite old ones as well such as the Peshitta Syriac) it is in there. Who took it out or added it? We don't know for sure nor can we claim to know since we don't have the autographs. We do know that it appears to consistently be in Luke, so what is the problem with it being in Matthew as well?
The problem with the Greek Orthodox commentator is that he interjected into Hebrews something that wasn't there. Noone disputes that Jesus is the WORD. His implication is that the Bible said Jesus was the firstborn WORD and he then took that to say if firstborn WORD only means first with others following then there would be other "WORDS." The Bible doesn't use the phrase firstborn WORD though. Such an argument was dishonest. Sorry. That's how I see it.
"Text Proofing" should be done cautiously. But caution and arrogantly tossing on Scripture because you buy into some belief that it is somehow untrustworthy is another.
The Septuagint, incidentally is a bit older than the manuscripts used for translation of alternate Greek Texts from the Textus Receptus. By your logic, it should be better. Incidentally, in this case I would agree knowing the care that the Jews took to preserve their Scripture. They wouldn't have stood for some insertion.
Consider the context of the manuscripts found then make a decision as to which is the better.
The Codices are complete works. Textual criticism is based on complete works being compared to existing fragments. Based on that, the Vaticanus and Sinaiticus have been used since their discovery as the more correct version.
would agree knowing the care that the Jews took to preserve their Scripture. They wouldn't have stood for some insertion
Well, the Septuagint (fragments) and the Dead Sea Scrolls were written by the Jews as well, and they don't agree with the fragmetns that correspond to the Masoretic Text.
Besides, the New Testament uses almost exclusively LXX as its source.