Micheal would never touch Tom no matter what he did, as long as he doesnt do anything to physically hurt Micheal or his family. Tom could have left and done whatever he wanted to and there would have been nothing to worry about. Micheal respected and loved Tom more than any other of his brothers i believe. I know what everyone is going to say, Mike had his brother killed! Fredro, weather he knew it or not, was involved in a plot to have Mike killed and also effectively overthrow the Corleone family, not accept a RESPECTABLE, ILLEGITIMATE job. If anything Micheal would have been jealous of Tom and the move he was free to make.