I absolutely love Rizwan the WK batter for his consistency but in T-20 he needs to up his game drastically as far as SR is concerned. In modern T-20 cricket, it's a crime for an opener to have a 126 SR after playing 80 matches.
If he can improve his SR, let's say 140-145 with an average of 40-ish or even 38-ish then he would be a more dangerous T-20 player.
Two players of the Pakistani team, Babar Azam and Mohammad Rizwan, have a big responsibility. Victory and defeat depend on them. As a result i think their normal batting is disrupted due to the additional pressure of the team along with his own batting. But I think SR can be increased if two or three good and reliable batsman like them add to the team. I believe any batsman will do well if he can play without pressure. If I see the SR of few Indian T20 players first Ishan Kishan his SR is 132, Rishabh Pant 147 and Suryakumar Yadav 136. I agree with you that Rizwan should try to increase his SR.
In the last T-20 WC, it was Pakistani middle order who put their foot down many times and scored valuable runs so it's a positive.
Imagine one of the openers (Babar or Rizwan) start playing with the intent and then they have Masood at 3 (he kinda reinvented himself) and Shadab, who is already an exciting LOIs player. Build a team around these batters and you got a nice combination.