Compelling case TB, but as Al Pacino might say, let me play "Devil's Advocate" here.
1. Solozzo shooting - Michael saw first hand that there was going to be another assassination attempt at the hospital, and
he brilliantly inmprovised the moving of the bed to another room, and stationing Enzo outside. During this he calls Sonny who obviously tells him "don't panic," which clearly offends him. I think Michael realized that Sonny wasn't up to the job, and that he had to become more involved. His moving "I'm with you now Pop" scene is followed by him and Enzo pretending to be armed guards, for which he gets belted in the mouth by Mac after he goes wise on him asking "how much is the Turk paying you to set up my father (BTW Hagen and his court order got from the all on Long Island to Manhattan almost as
quickly as that orange juice appeared in GFIII) ?" The following day he is in a key meeting with Tom the two capo regimes and Sonny. He witnesses Sonny's ineptitude again as
he is bragging about having a hundred button men on the street, after killing Tatt's son as a payback for the hospital (an overreaction IMHO) and he then witnesses Tom talking Sonny into negotiating with Sollozzo. Since he was delegated to be the one to go to the meeting and since he recognized Sollozzo was going to "kill Pop," he understood Sol had to be eliminated. Yes, it is true they could have gone to the papers and it is also true that with the political connections intact they could have ruined Mac and had Sol deported, but that wouldn't have solved anything. The war was already going on. If Michael went to the restaurant and told Sol "As you know I am not really involved in this, so I'll run your proposal by the business end of the family and I'll get back to you," what would Barzini have done once he saw the story in the papers about Sol and Mac? Not too long IMHO and they'd be back to square one. So killing Sol was his best shot so to speak, at saving his father.
2. Choosing to be Don. After killing Sol and living in Sicily under the tuteledge of Don Tomassino for a long time, and after watching his bride die, and learning of the death of Santino, he had no one to turn to except Vito. It was too late for him to become Senator Corleone, or Governor Corleone because regardless of the way Vito kept him from a murder rap, rumors would circulate about the shooting and the missing year or so in Sicily. In other words he had already crossed the Rubicon and he was now headed to the only real destiny he ever had.
3. Not Going Legit-A. Yes he continued to run things through Pentangeli, and he was willing to compromise with the sleazy tactics of the Rosatos in order to get hold of Roth's action in Cuba (more or less legitimate....no worse than the teamsters) and make a move in Vegas on Klingman. This is more financial white collar crime than being a street thug, and it moves him in a direction toward legitimacy.
4. Not Going Legit-B. To get to make the Immobiliare deal he did have to make a significant deposit with the Vatican bank, but there is nothing illegal about it. In addition he had created foundations for Sicily, and had the hospital named for Vito....all legitimate. He also "sold all the casinos," and it was his intention to retire from the commission the night he paid back all the investors in Atlantic City. He told them
"Our business is done." This after learning he had been nearly stabbed in the back on the premise that the "Pope is very ill). He had no idea there was going to be a hit, and he told the commission members who wanted in Immobiliare they could not be. He thought he was getting out but he was being dragged back in. Moreover, now he understood that the so-called "legitimate world," i.e. the Church and the largest real estate conglomorate on earth were as crooked as the mob.
5. Sitting ducks at the Opera. Having relinquished control to Vincent, he did put himself and his family in danger by the way
he attended the Opera. What can I say? Don Michael was slippin'.
