There may have been a reason Michael allowed all this to play out. At that point Michael knew that Zasa knew that he (Michael) was preventing Zasa from rising up in the Commission. For some reason, probably preventing a war, Michael was completely against having Zasa killed, but embarrasing him like that in "public" got just the reaction Michael wanted...a declaration from Zasa that the two of them were now "enemies." Of course Michael underestimated Zasa, and did not see the Zasa-Altobello alliance (thats what he gets for having George Hamilton as a lawyer.....Hagen would have figured this out) coming, and he was clueless about the helicopter attack. This was a terrible tactical mistake.

Of course once Vincent an Neri rescued him from the attempted hit, Michael, who was plotting against Zasa in a rather feckless way, indulges in self-pity by claiming he is beind "dragged back in" when in fact he was never really trying to get out.