By case law he's fine, but right on the edge. That's why it would be essential to know what he would have done if the kid was an atheist: it reveals whether he actually has a secular purpose.
I would have preferred the judge send him to a three-month or even one-year treatment program, and required attendance at AA for the duration, along with having him give talks to younger kids about the consequences of drinking -- like killing your own friend, even by accident.
Though since no one is challenging it, for that jurisdiction that approach is legit.