I have to admit that I am thoroughly puzzled by this thread.
I have translated the Digha Nikaya into Norwegian and now I am working my way through the Majjhima Nikaya. In addition I have translated parts of the other Nikayas. The more I translate, the more I recognize modules in the texts. Part of my work then is to recognize modules, search for them in what I have already translated, and then mark, copy and paste. After copying and pasting, a final check to see if there may be minor variations, for example in names etc.
The texts that I already have translated thus functions as a database for those standard text modules, and the modules can be combined in different ways.
This shows something of what was going on in the minds and memories of the early monks who preserved the texts orally. I am deeply impressed to see how their brains worked like a computer with a good text processing program. They memorized texts, recognized basic text modules and often recombined those modules into new text units. Most (or all) of the texts in DN and MN consist of those modules, edited and recombined in new settings.
Thus it can be argued that only the shorter texts in the Anguttara and the Samyutta are original texts, since they often consist of only one such module. Or we may take the opposite view, and say that the shorter one-module texts are extracted from longer texts containing several modules. From such a view one might argue that the MN is more original. We simply do not know for certain.
So what? Are the Suttas all forgeries, then? Or are all the short Suttas forgeries? Or are all the long Suttas forgeries?
Those who bring the word "forgery" into this debate, obviously do not understand the nature of this process of memorizing and transmitting modules. And to criticize ONE of the long Suttas for consisting of modules, when this is a demonstrable aspect of ALL the longer Suttas, seems rather strange to me. This Bhikkhu Sujato who seems to be the one who brought up this theme, must be very ignorant of the Suttas. Or, if he knows the Suttas, has he got some hidden agenda by singling out ONE of the long Suttas for criticism?
I do not know. But it is difficult to take such a criticism, based on deep ignorance, seriously.