I didn't believe this because leviticus forbids Jews to eat human flesh (which also proves that Jesus was speaking in metaphors at the last supper rather than advocating literal cannibalism as the Catholic Church teaches).
But in the rafzen article (which will soon disappear from wordpress) a former rabbi said that there are exceptions in scripture that permit cannibalism on certain occasions.
So I looked for verses in the pentateuch that permit cannibalism and found one: Deuteronomy 12:20
https://www.biblegateway.com/passage/?search=Deuteronomy+12%3A20&version=KJV
"When the Lord thy God shall enlarge thy border, as he hath promised thee, and thou shalt say, I will eat flesh, because thy soul longeth to eat flesh; thou mayest eat flesh, whatsoever thy soul lusteth after."
It's pretty clear that this is a conditional permission to eat all types of flesh on special occasions, not a vacuous statement that eating meat which you are always permitted to eat is, on these occasions, also permitted.
Most of the translations falsify the scripture, saying that you may eat regular meat "as much as you want" (Complete Jewish Bible) or "whenever you desire" (English Standard Version).
The literal words say that you can eat "whatsoever" flesh you "lusteth after".
So this information checks out. Finkelstein, real or not, appears to be telling the truth.