Hmm wonder why I didn't see this the first time ;)

I think another problem is the hardcoded lack_of_motivation line in the RTW and BI exes that went active the day MTW2 was announced. You can work around this by increasing the modders' support cost to at least 10000 denarii which would buy enough beer for the lot.
If that doesn't help you can also try changing the UI so that it says "A total conversion for MTW2" which apparently increases your chances of the lack_of_motivation line becoming inactive at random intervals.