The move makes a certain amount of sense. After all, Minnesota is full of white people, and white people are exactly the people Mitt Romney is counting on to win this election. But there are a few reasons to doubt Fehrnstrom.
Minnesota hasn't voted for a Republican president since 1972. The Republicans held their convention there in 2008, and Obama still won by 10. The state's last Republican senator won because his opponent died right before election day, and its last Republican governor won two terms with the help of a third party. In the 2010 Republican wave election a Democrat won the Minnesota governorship. Mitt Romney came in third in the Minnesota caucuses. Ron Paul beat him. No poll has shown Obama doing worse than a five percentage point lead among likely voters in Minnesota. In other words, Mitt Romney is not going to win Minnesota.
No, the point of the "we're buying ads in Minnesota" move is the same as the "we're gonna win Nevada" line, which is to get people to report that Romney is so confident now on account of his "momentum." It's actually pretty silly, because a) it doesn't work, as George W. Bush showed in 2000, and b) all political reporters now see through it, even if they still do their job and report what the campaign says.
That's not to say that the move is purely about displaying "confidence." It's also, I guess, about getting some ads seen in western Wisconsin. Polls are close there, and every vote counts, even in the parts of Wisconsin where hardly anyone lives. Also the campaigns have a lot of money, and buying ads is a thing to spend money on, even if buying ads is sort of not really worth it most of the time.
Right now, basically, there is not anything the campaigns can do besides just keep forcing their candidates to fly around the same few states and say the same stupid things to journalists about how confident they are that they will win all the states. (Pennsylvania's still totally in play!!!)
We're in the horrible home stretch of this thing. Don't trust anything anyone says, besides Nate Silver and Steve Kornacki.