No one said Irenaeus was infallible but he is the closest resource with direct knowledge as to the timing of the writing of Revelation. To directly contradict someone who studied under the person who was a direct Apostle of John is foolish. His statement is the most authoritative we have as to the time. His statement of when Revelation was written and his statement of not knowing the name of the Anti Christ puts Preterists in the category of error.
1) That's basically a Romanist/traditionalist argument. Fine if you wish to make it and hang your hat on it. It only carries weight with other traditionalists.
2) His statement is not as crystal clear as you make it out to be. There are original language expert who cannot say for sure that his comment was a direct reference to the book of Revelation.
3) You're treating his somewhat unclear words as if there are infallible and trump all other arguments.
4) Many good conservative theologians disagree with the traditionalist AD96 date preferring a pre-AD70 date.
5) You choose to ignore or discount all the counter arguments. You can't win an argument that way.
6) Using this then to claim preterists or other non-traditionalists are in error is pure cop out.