I think this (and in fact any fixed number of mafia with an increasing number of town) should converge to 50%. As t grows large, the probability that all of the mafia are sorted into either hell or heaven by the time that the game reaches a judgment day grows to 1, because like mith says they're effectively randomly being put into "slots" and the number of slots that could be alive in a judgment day stays fixed. But then effectively all 3 mafia are being randomly sorted into heaven and hell, which should give a 50% chance that the majority wind up in heaven and a 50% chance that the majority wind up in hell.Let's try 3 mafia, 2t townies
This appears to converge to 25% EV from above as the number of town grows arbitrarily large, just like the last setup.
That said, if this is some programming error, I am interested to see what the setup that these actually are the EVs for is :p