Well what this part of the circuit does, is obvious, it is an "inverting summing amplifier". Which means, that it sums up the two inputs. Why he used two inputs, instead of the one in the patent Fig 4 is another question. Both inputs first have a voltage follower for decoupling and then they both go with the same resistance in the inverting summing amplifier. Which means, their input is added equally (summed up).
Maybe he just wanted to have the option to be able to have different circuits telling the VIC at which voltage it should run. If he used it is another question. Did he wire both of the OpAmp inputs to the Sub-D Plug?
But all in all, I don't think that this is really an important point, as it only controls the analog voltage level.
IMHO the really interesting part is the workaround he did with the comparator input, and the fact that he routed 3 different signals from the Q8-region to the connector. The big question is, which signal did he really use to drive the TIP120? And the other question: Where does the red wire, which is connected to the neg of the primary (by the blue wire), really go? It looks like it is going where actually one of the resistors should have been soldered. But it looks like this resistor was not soldered, but instead the ground connection of it was used for a capacitor and the other connection for the red wire. If it was really connected like that, then the actual circuit is a completely different one!!! It would behave completely different, than the one in the patent circuit!
