Titus Flavius Clemens (c.150 – c. 215), known as Clement of Alexandria, was a Christian theologian who taught at the Catechetical School of Alexandria. A convert to Christianity, he was an educated man who was familiar with classical Greek philosophy and literature. As his three major works demonstrate, Clement was influenced by Hellenistic philosophy to a greater extent than any other Christian thinker of his time, and in particular by Plato and the Stoics.[1] His secret works, which exist only in fragments, attest that he was also familiar with pre-Christian Jewish esotericism and Gnosticism. Among his pupils were Origen and Alexander of Jerusalem. Source
I believe Clement of Alexandria was around long before Martin Luther, Rheims New Testament, or the King James Bible by about 1,400 years.
Clement of Alexandria is a red herring in this discussion.
The article says that his works "show no knowledge" of this particular pericope.
That is a meaningless point.
If Clement had written an exhaustive commentary on Mark that discussed all the verses except for these, then it would be a meaningful discussion.
But Clement wrote only a few hundred pages that survive, and they are works of exhortation - not textual commentaries.
He quotes less than 5% of the Bible - does that mean he had no knowledge of 95% of the Bible?
This is the definition of a weak argument.