TB, at least part of Michael's church contribution motivation was his effort to try and redeem himself for his murder of Fredo.
No doubt about that.
His invitation to the press though is puzzling. As you state, it may have been due to his continuing effort to appear legitimate. Maybe he was fooling himself. Maybe by then he was trying to convince himself of his legitimacy with the trappings of legitimacy.
Michael fooling himself about "legitimacy" was his undoing throughout the Trilogy. A serious essay could be written about how frustrated Michael was about "legitimacy" and his failure to achieve it.
By the way, since I teach some law, I appreciate your post about the complexities of American due process and the relative ignorance of so many people about that process and its complexities. Roth's knowledge of Michael's hidden links could have set the forensic accountants on a quest to expose those links.
Thanks, Oli.

I see it as part of FFC's fanatical attention to detail, including legal details that we can appreciate.