I just posted this in a similar thread -
I teach English as a second language - there is a BIG difference between conversational English and having to respond to questions from interviewers who OFTEN speak quickly, throw in a few or more difficult or techincal words - which sometimes are mumbled or mixed in a line of other words not enunciated. Having a translator will prevent Anderson from either saying, "Excuse me? What?" or not knowing the meaning of a particular word and just 'guessing' at the answer or nodding and looking stupid. In fact, any fighter (Fedor, etc) will benefit by listening to English and then having the meaning reinforced by a translator (and as someone else mentioned, for the benefit of native listeners).
So Bisping, if you were okay at and learning Portugese (and listen to Anderson, he's not any better than fair), would you want to conduct an interview in front of millions of people without an English translator just to facilitate things for ya?