While we don't have any evidence to support this rumor, it is quite plausible. Like I wrote at the time, Apple could make the iPad Mini in Brazil for the good press.
Think for a moment about all the many stories about the working conditions in factories making Apple products. There were a lot of them, and even though Apple's working conditions weren't any worse than the average Chinese factory Apple still got a lot of bad press (it is easy and fun to bash Apple, I know).
Moving the production to the new factory complex in Brazil would give Apple an opportunity to show that they've improved the working conditions. In fact, Apple's already getting some good press for the new factory:
Labor activists point to Foxconn's record in Brazil to show that it and Apple can make products under lawful conditions while paying workers decent wages when the local environment requires it. And they believe that Apple and Foxconn have been taking advantage of Chinese workers simply because they believe they can get away with it.
I can picture Tim Cook getting up on stage and talking about the new factory, can't you?
That is as true now as it was then so it would not surprise me if that is indeed why the iPad Mini ended up getting made in Brazil. And given that the latest rumors say that invites will go out on 10 October for the iPad Mini unveiling on 17 October, it pretty much has to be in production somewhere.
via Mac Otakarina