After thinking about it this for awhile, I've got an interesting prospective.
My first thought was to punish him, and kick him off the team. But, after thinking, how does that help him? He is so close to finishing his degree, and getting himself and family, out of a rough neighborhood. Is it better to jeopardize the future of Mike for the sake of following suit with the almighty "du lac"?
As far as I know, ND is not bound by any act to follow precedent. Treat the situation individually, and do what is best for Mike, not what some gay policy book says.
1. Make him go to bi-weekly alcohol meetings from now til the end of football season or graduation. If he misses one...he out.
2. Random alcohol tests.
3. Make him do charity work with kids weekly.
4. Make him volunteer 1 night a week in the ER so he can see what the consequence of a DUI can look like.
5. No slip ups. If he gets a parking ticket...he's gone.
6. Give Manti a free shot on him with a 50 yard sprint to the target.
All those things will help Mike, kicking Mike off the team and out of ND will not. And that goes for all students, by ND kicking them out is not forgiving, and does not serve the student.