My theory is predicated on the Commission simply using that as a means to an end. That is, it's no secret to the Barzinis, Tattaglias, Straccis and Cuneos that Michael was indeed the perpurtrator of the murders, but merely that after the years of bloodshed, if clearing Michael meant the peace then they would go along with it.
If all of this is true, then how does Barzini account from that when he underestimates Michael in the future? Unless, they believe that Michael was merely the trigger-man and that the operation to kill Solozzo and McCluskey was planned by Sonny and the capos.
I think that everyone would assume it was Michael. For instance, I don't see any reason why Barzini and Tataglia wouldn't know that Sollozzo had set the meeting with Michael.
I think you're right, they'd think he was merely the trigger man. I think Michael was underestimated as a Don -- for strategy and leadership -- more than for courage or street smarts.
