OK, so he really wasn't talking about seminary (which makes me a faint-hearted originalist like Scalia I suppose).
But in a speech to the Federalist Society he was asked a question on how law schools could teach lawyers to be better advocates. Scalia admitted he was probably old-fashioned on this, but he believed a law school should teach students a body of knowledge and a process of analysis. The rest, he said, could be picked up in any courtroom. Law school is a professional school, not a trade school, Scalia said.
This sparked my mind to think about seminary. Many treat seminary like a trade school, where you go to learn how to be a pastor. So they load it up with all kinds of practical ministry classes.
I think seminary ought to teach a body of knowledge and a process of analysis. The rest can be picked up by hanging around a church and a good pastor.
If you go to seminary and learn methods of ministry, you will soon be outdated. The body of Christian knowledge and sound principles of analysis will serve you well through changing times.