Gaius of Rome Attacks Another Gospel of John

I have always said that Gaius is not attacking our canonical gospel of John but the gospel that was in the hand of Polycarp and which the Smyrnaean bishop attributed 'to John.' This is a very complex argument and requires me to post a lot of research from my Against Polycarp book (which happens to have an introduction from David Trobisch). Yet let me break it down to one of its simplest arguments:

But again these same men accuse the holy evangelist, and even more so his gospel, because, they say, John spoke concerning the two Passovers that the savior had made, but the other evangelists concerning only the one Passover. And the idiots do not know that the gospels not only confess two Passovers but also say that they were only the first two, which along with that in which the savior suffered his passion make three Passovers in all which have been dealt with in the preaching. [From Epiphanius, Panarion 51.22]

Now Epiphanius is certainly self-satisfied with himself by proving how 'idiotic' Gaius and his adherents are but notice that Eusebius makes clear that 'Gaius was a very learned (λογιωτατου) individual who lived in Rome.' A learned man couldn't have been so stupid so as not to be able to count the number of years the Gospel of John went on for.

Irenaeus proudly counts three or even four Passovers so we can't imagine that only the Catholics know how to count. What is at the bottom of Gaius' insistence that 'the Gospel of John' used by the adherents of Polycarp only had a two year ministry of Jesus?

They were using a Diatessaron attributed to John (the Diatessaron only has two years or two Passovers in the ministry of Jesus.

The point is that Irenaeus changed the Gospel of John to get away from Gaius' Mark vs. John line of reasoning (the same pattern manifests in Tertullian's original source).

Ultimately Irenaeus was successful (until we discovered the hidden thread which takes us back to the original argument). More on that later. I've got to go to bed ...