Why Does Ephrem Give So Much Significance to Zacchaeus?

When you actually look at the story of Zacchaeus there appears to be nothing to it.  Jesus comes to Jericho. A short guy climbs a tree.  A short guy climbs down from a tree and tells Jesus I give half my money to the poor etc. Jesus likes Zacchaeus.  Jesus leaves Jericho.  Why then does Ephrem consistently interpret the story of Zacchaeus as the single event during the ministry narrative which 'solved' the problem of Adam's sin?  An example from the Commentary on the Diatessaron:

Zacchaeus was praying in his heart as follows, "Happy the one who is worthy that this just man should enter into his dwelling." The Lord said to him, "Hurry, come down, Zacchaeus." Seeing he knew his thoughts, he said, "Just as he knows this, he knows also all that I have done." He therefore said, "All that I have unjustly received, I give back fourfold." Hurry and come down from the fig tree, because it is with you that I will be staying. The first fig tree of Adam will be forgotten, because of the last fig tree of the chief tax collector, and the name of the guilty Adam will be forgotten because of the innocent Zacchaeus.

See, Lord, I give up half of my goods and all that I have received unjustly, I give back fourfold. Wherefore, this day salvation has come into this house. Let the apostate people be confused by the swift discipleship of him, who was yesterday a thief, but today has become a benefactor, yesterday a tax collector and today a disciple. Thus Zacchaeus, left behind him the just Law and climbed up, by way of symbol, a dead fig tree, a symbol of the deafness of his listening. But the symbol of his salvation was depicted through his ascent. For he abandoned the depths below, and he went up into the air in the middle, to contemplate the elevated divinity. Our Lord hastened to bring him down from the deaf fig tree, as though symbolically from his way of life, lest he continue in his deafness. While the love of our Lord was becoming fervent within him, it consumed him so that his former habits and that he might be fashioned into a new person through it. So that he might know there was a new offspring there, [the Lord] said, 'he too is a son of Abraham.' [Commentary on the Diatessaron 20, 21]

The point of course is that most scholars read this exegesis and quietly laugh to themselves, 'ha, ha, these Eastern writers are so good at making shit up.'  But what they fail to recognize is that this is exactly the context of Clement of Alexandria's understanding of the significance of the passage - i.e. that it goes back to or is connected with (perhaps better yet, is the conclusion for) the Question of the Rich Man.

It is established that the rich youth knows all the commandments but - in the Marcionite gospel - Jesus gives him a commandment of his own - 'thou shalt not lust.'  Those who read this statement in the anti-Marcionite writings and Clement of Alexandria that this is the same thing as saying 'not to lust after one's neighbor's wife' miss the point entirely.  Jesus is setting forth the commandment for the attainment of a 'lustless' state.  One is not justified merely in lusting after one's own property but not that of a neighbor.  Instead, lust is 'cut out' - presumably through the act of ritual castration.

Ephrem here provides us here with all the pieces to complete the understanding established in Clement's Can the Rich Man be Saved - namely establishing that not only was Zacchaeus 'resurrected' (= abandoned the depths below), not only was ritually understood to have been 'in the underworld' with Abraham (= cf. Petersen and Phillip's observation - developed in large part from Origen's citation of the Gospel of the Hebrews - regarding the Diatessaron's placing of the Rich Man and Lazarus between the Question of the Rich Man and this narrative), most important of all is the understanding that in the underworld the rich man recognizes the emptiness of the promise of the Law.

When all the other pieces are laid down in a row we can easily recognize that:

1. Clement of Alexandria's gospel took the form of a 'Diatessaron' (cf. Ammonius of Alexandria's fabled text)
2. the Marcionite text took the form of a 'Diatessaron' (cf. Casey's article on the Marcionite Diatessaron) 
3. likely all early gospels shared this basic narrative

The construction of the Catholic 'fourfold gospel' was likely developed as a cento principally to 'assist' in making this key section of the gospel narrative 'disappear.'  Zacchaeus is not a name of a disciple but a title - a recognition of that disciple's 'purification' through death and resurrection from the Law.