Josephus wasn't a church father, he was a traitor to his Jewish people, he left his military command in Israel, and joined the enemy in Rome, being their propaganda minister, being rewarded with a Roman palace, women, and monies for his service to the Roman Emperor
Your 100% correct, no early church fathers Justin Martyr, Iranaeus, Hippolytus, even mentioned 70AD, let alone claimed it was fulfillment of Matthew 24
The Jesuit Roman catholic was the inventor of the preterist teaching as seen below
Wikipedia: Preterism
Historically, preterists and non-preterists have generally agreed that the
Jesuit Luis de Alcasar (1554–1613) wrote the first systematic preterist exposition of prophecy
Vestigatio arcani sensus in Apocalypsi, published during the Counter-Reformation.
The term
preterism comes from the Latin
praeter, which is a prefix denoting that something is "past" or "beyond". Adherents of preterism are known as
preterists. Preterism teaches that either all (full preterism) or a majority (partial preterism) of the Olivet discourse had come to pass by AD 70.
Interpretation of the Great Tribulation
In the preterist view, the Tribulation took place in the past when Roman legions destroyed Jerusalem and its temple in AD 70 during the end stages of the First Jewish–Roman War, and it affected only the Jewish people rather than all mankind.
Christian preterists believe that the Tribulation was a divine judgment visited upon the Jews for their sins, including rejection of Jesus as the promised Messiah. It occurred entirely in the past, around 70 AD when the armed forces of the Roman Empire destroyed Jerusalem and its temple.
A preterist discussion of the Tribulation has its focus on the Gospels, in particular the prophetic passages in Matthew 24, Mark 13, Luke 21, and the Olivet discourse, rather than on the Book of Revelation. Most preterists apply much of the symbolism in Revelation to Rome, the Caesars, and their persecution of Christians, rather than to the Tribulation upon the Jews.
Jesus' warning in Matthew 24:34 that "this generation shall not pass, till all these things be fulfilled" is tied back to his similar warning to the scribes and the Pharisees that their judgment would "come upon this generation", that is, during the first century rather than at a future time long after the scribes and Pharisees had passed away. The destruction in AD 70 occurred within a 40-year generation from the time when Jesus gave that discourse.
The judgment on the Jewish nation was executed by the Roman legions, "the abomination of desolation, spoken of by Daniel the prophet." This can also be found in Luke 21:20.
Since Matthew 24 begins with Jesus visiting the Jerusalem Temple and pronouncing that "there shall not be left here one stone upon another, that shall not be thrown down" (vs. 3), preterists see nothing in scripture to indicate that another Jewish temple will ever be built. The prophecies were all fulfilled against the temple of that time, which was subsequently destroyed within that generation.