The only reason this fight is likley still happening is because its the fight GSP wants. Diaz never earned a shot so punishing him is one thing but they are taking the fight away that Georges wants.
Diaz is simply scared I am convinced its true because in the UFC he has met his media obligations except when it involves fighting GSP. Diaz doesn't want the fight and is trying to play it off as some anti establishment bullshit to save face.
The media obligation for GSP vs any other person he has fought is probably a night and day difference. It's noted he doesn't like the spot light. Maybe this is his way of dealing with the pressure,etc of the magnitude of this fight. We all expected this BS from nick, but everybody knows he will show up to fight.