This is another plot weakness in III. The Vatican already had washed away Michael's sins by making him a Papal Knight, thanks to his charities. Why voting to give him control of a real estate company provide further cleansing? Why would he need it? And, it's one thing to bestow religious honors on a questionable character like Michael in the service of "charity"--all major religions do, under the rubric that the money is going toward charitable ends (no matter how it was made). But, the Vatican would be taking a very big public relations risk by putting their share of a huge, money-making company into the hands of a supposedly reformed Mafia Don so that he could get richer. Michael would be taking a big risk, too: It'd look like his Papal Knighthood was a bribe for bailing out the Vatican Bank and getting Immobiliare.

LW makes a good point about continuity. In this instance, I see a continuity from Michael telling Kay that his father is no different than other powerful men with responsibility for others; to Nevada, where, as Geary puts it, "...the way you pose yourself and your whole f....ng family" as legitimate with his big donation to the university and his lying under oath; to his hooking up with a corrupt senior cleric of the Church in another corrupt scheme to make him look "legitimate."