Basically the interview is a no-win situation for the player. An innocent player is dragged through the mud again, and guilty players either have to admit, based on no real evidence, or deny and face a double penalty for lying to the NFL if more evidence comes out.
Let's face it, other than punters and kickers, is there anyone in the NFL that you'd be stunned to find was juicing, so even a false accusation is damaging, particularly to endorsements.