I may have found a solution. If you're stuck on the part where you escorted Pafnuty to Moscow, waited two weeks (or in my case some 60+ days wandering around trying to find him) and still can't find Pafnuty, then what worked for me was this. I had to make Moscow and the Muscovite faction hostile to me and then I went to Moscow and the choice to talk to Pafnuty appeared. See, I was friendly with the Muscovites at the time, and apparently they assumed you'd be hostile with them and forgot to add that choice in. To get hostile with them, I just attacked the nearest Muscovite scout or caravan. Hope this helps those who are stuck on this.