Michael has his hands and mind in the GFIII massacre. Also, reagrdless of one's motivation, a transgression of the law (or morality) is still that, a transgression.
So, while he no doubt wanted out, he did not completely sever his relationship with what he wanted out of until it cost him the ultimate - the death of his daughter.
Well there is no direct proof that he helped Vincent plan anything. Moreover your point that he did get out after paying the terrible price of his daughter's murder. That was his penance.
