That's what I find strange. If they had sold 15 or 20 millions, they'd more than gladly say so instead of "more than 10". Even more so to make a point. Unless they're amateurs, every public message is scrutinized before being released.
They sold "more than" 2.5 million copies during EA, Swen said as much in an interview shortly before or after the release - I don't remember exactly when. So we only know it's gone from 2.5+ to 10+ since August, which would be relatively quick when you compare to many other games, even if it were only 10. But, as you said, the 10+ could be an old number. It would actually make more sense, especially when you consider the Xbox and PS5 consoles.That means very little. When he says "a very short space of time" it actually might not mean "to the present". It could refer to literally any time period post launch i.e. 1 month, 2 months, 6 months etc.