The trouble is that buckling to his wage demands could have a whole load of bad ramifications in the future. It sends out a message to the rest of the players that they can run their contract down, demand higher wages and the club/AW will eventually give in through fear of loosing them on a free. You also have the whole "if Nasri's on that much then I want this much" for any player who plays well next year.
And to be honest, if Nasri thinks 3-4 months of top quality performances in the space of 4 years warrants him being the highest paid player at the club, then he can quite frankly fuck right off!