If he actually ends up metagaming then I'd bring it up with him and tell him to either stop it or leave the game.
Why is one of the first reactions often "stop or leave"?
It's better for our gaming community to work with people then it is to work against them. There are often gaming or social faux pas that players make, some big, some minor. The thing is to gradually smooth out the rough edges of new players, just like you would with any other social group.
Our society today has a lot of information on the Internet about games. People grow up today thinking that it is perfectly acceptable to cheat in games, use cheat codes, know things about mobs, etc. If that behavior is not what a DM likes, then he should work with the player. It's not that I condone cheating, but our young people are being taught that it is becoming more and more acceptable (just look at the percentage of cheating at college campuses). Having the group frown on the activity and explaining it to the player without a threat is the way to go. Sure, he might still backslide once in a while, but the more the rest of the table reinforces behavioral expectations, the more likely a person is to coexist and become an asset to the table.