I find Scott Hahn to be a great man, in many ways. Now to be honest, I personally don’t agree with - or have come to disagree with - some of the ideas which he has been proposing (for example, the ‘Fourth Cup’ typology and the identification of Melchizedek with Shem), but I still respect him as a very able scholar and theologian.
Rome Sweet Home was a good read, I’ll tell you.
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I would agree that these are fairly minor disagreements. In terms of the fourth cup for example, certainly we really ought not to see Judaism as somehow fixed and continuous, or even that Jewish traditions today have the same kind of consistency as even the Catholic Mass has. There was never the central authority in Judaism that would have made this possible. Traditions develop and grow and transform into a myriad of different variations according to the times and local customs.
Still, I think that the basic form of the Jewish Passover meal is present in the Last Supper and the crucifixion of the Lamb of God. Drinking in Judaism was likely very ritualized from early times, and is one of the reasons why Jews have never suffered from alcoholism as those from other cultures that drink alcohol often do. A fourth cup or more specifically a final cup denoting the end of the ceremonial drinking does seem to be in line with some of the symbolism within the scripture at any rate, and does give a fuller picture of the richness of the text.
More than this though, the nature of religiously inspired text is that no words are wasted, and every event that transpires is meaningful on a theological level. If not the fourth cup, then the last drink by Jesus is telling us something else that would further our spiritual growth in some way.
I do think you make a good case that Scott Hahn may have oversold us on the point of the Fourth Cup as far as history goes, but I nevertheless do see the same basic form of ritualized drinking being the constant, with the last cup bringing about the consummation of the entire ceremony.
As far as Melchizidek and Shem, while I do not know the whole story on this, what is important that Scott Hahn does very well, is to open up an understanding of the Gospel in the light of the whole of the Judeo-Christian tradition. It is important too, to also understand that a lot of the rabbinic and mishradic commentary on Scripture are not meant to be seen as literal, but are commentaries that often take an outlandish and even bizarre perspective which attempt to reveal a deeper truth about the Scripture itself. What I would be more interested in then, is not whether a son of Noah and Melchizidek are the same actual person, but why this would have been important to the commentators in the first place.
Sacred history may have introduced the world to linear thinking, but theological symbolism is in no way linear. Every symbol has not only an inner meaning that reveals the reasons for the scriptural event, but there are layers of meanings there to be discovered as well. There is no one final meaning to any symbol. Symbols point us to a transcendent truth, which is infinite and eternal.
Difficult history between Christian and Jews has often cut us off from some of the symbolic meanings of the text. Scott Hahn has been very effective at reintroducing us to that heritage, and giving a fuller picture of the true depth of scripture as a result.
Modern Protestant theology that he followed in which modern history and Armegeddon had been portrayed as the deeper meaning behind Scripture has played itself out to be pretty much a dud. The related ‘gospel as historical plot’ that consumed Hahn’s younger years has turned out to be fruitless for him as far as revealing what Scripture was actually trying to tell us.
I think he has opened a door for us with the kind of theology he does, with seeing the Mass as the better expression of the Book of Revelation, or of looking at the Judeo-Christian tradition in its entirety for the better understanding of the the Passion of Christ.
Many Protestants(and Catholics) turned to literalism as a reaction to the higher criticism of the bible that confronted Christianity in the last century. Scott has in the end rejected that, and has us look for the meaning of Scripture with history mainly as the backdrop only, but not the central feature.
I agree that it would be a mistake to make dogma out of his theology. His is not the final word on Scripture; he has merely opened a door for many Catholics nevertheless on how better to look upon Scripture to discover the meanings that it still has for our lives.
). I mean, I can still acknowledge Scott’s influence and knowledge without totally agreeing with all that he says: that’s what free will is for, after all. 
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