In truth, the developers at EA Canada weren't sure at the time how far they could take the feature. The video itself only showed a commentator pointing out someone's unhappiness with an offside call, not a yellow card. I was later told that developers wanted to include booking for dissent, but a big concern was, in standard team play (or multiplayer), who on the team would get the yellow card. If it was assigned to a player who had already picked up a yellow card, then he would be sent off, and then the swearing really begins. I suppose also, in local multiplayer, they'd have to control for your opponent or someone else in the room swearing at the screen in an effort to get you booked, too.
Evidently it was too complex to implement in this year's game, as that video above declares: No one will receive a yellow card for swearing in the Kinect microphone. However, it will affect in-match commentary, storylines for your Pro or Manager, and can also result in stricter officiating for the remainder of the match.
So all you potty-mouths can go forward and swear with near-impunity. And I'm told that FIFA has a very robust, multi-lingual vocabulary, which I'm sure everyone will want to put to the test.