It was his attempt to keep Tom focused on the "legitimate" side of the family business. Therefore, who better than Tom to represent Michael as a "legitimate" guy wrongly accused by the Senate subcommittee?
Yes, Turnbull, while it is true that Mike told Tom he was "OUT", Hagen was still deeply involved with the family "business". Afterall he was fully knowledgeable of the Senator Geary frame up, and the murder of an innocent "civilian", and female at that!
I think we sometimes lose sight of Hagen's ruthlessness and treacherous nature, due to his intelligence and calm demeanor. Lets not forget hes just as evil as everyone else...
