There is a reason why Pique is called "el presidente". He is a smart guy, probably by far the smartest in the team, but he never was and never will be captain's material. His comments about biased referees may result in trouble for him, but it was about time that someone gets vocal about it. From a psychological point of view this was a smart thing to do. Maybe things on that matter change for the better, at least for a short period of time.
Of course this goes above his responsibilities as a first team footballer, but these things happen if a club is without a president. Remember Koeman coming out in defense of Leo's contract leak last weekend. This isn't his job either, but it was a good gesture and necessary to back a player in public, especially after the whole saga in the summer.