Talented player, but if he's causing an issue in the dressing room and beginning to influence young players, then it is best to set a strict example early before it becomes common place.
Not the same, but one lad at our club had an attitude problem. When he got out it was always someone else's fault, he'd throw his gear, swear and basically being a total 'you know what'. We had a few u15s in the team, so we didn't want them doing the same. He was punished by the club, and it seemingly taught him a lesson because he's not done the same again (or at least when I've played).
Some might see it as harsh to ban a cricketer for a bad attitude, but for me, it can be needed in order to set the tone as to what is acceptable behaviour and what isn't. Hopefully Shakib learns from this and comes back more humble and down to earth. He is a good player and his team needs him to play and be a team player.