There’s three reasons I can give here.
I disagree with Imad and Rauf playing BBL but they don’t have anything to prove. Amir, however is trying to prove he’s fit to play ODI cricket and that Misbah, Waqar are wrong about him.
Imad and Rauf are playing cricket, not sitting on their bums. Amir is practicing batting in the nets these days. Azam Khan, for example, is also going to play the T10 league bit he has also been playing List A games. Amir can easily have played both if he wanted to.
Lastly, Imad already has his place established in the ODI team while Rauf has only played ODIs against Zimbabwe, and called up because of a lack of options. Even now there are a lack of new ball options after Shaheen, which strengthens Amir’s case for a comeback. So instead of performing, is Amir’s logic to wait for the rest to fail so that he can get called up?
Again, false dichotomy, this time by Amir. He could easily have played both List A and T10 if he wanted to.
Here are the other players who will be playing T10 and who have been playing in the Pakistan Cup:
Asif Ali
Usman Shinwari
Mohammad Irfan
Azam Khan
Sharjeel Khan
Amad Butt
Waqas Maqsood
Aamer Yamin