He's fine when the field is spread out and can work the ball around in the gaps, but as others have said he struggles in the powerplay because he cannot pierce the field and is reluctant to hit over the top and cannot play the ball with soft hands to take quick singles.
Sounds like he should be in at #4 in ODI- if early wickets fall & you simply need to consolidate to get to a score, he can do that. If the start is brisk he can play the "milking" middle overs well enough.
Honestly though if he wasn't at opener, Pakistan lose that game. Everybody else is getting knocked over for single figures you NEED an opener to bat long.
You cannot WIN that game in the opening 10 overs, chasing a reasonable total of 275. But you sure can LOSE it by losing 3 quick wickets playing too aggressively vs a team who's strength is fast bowlers with 2 new balls (& who's weakness is spinners to squeeze in the middle overs).
275 is so chaseable these days IF you bat the full 50 that why risk losing the game to worry about strike rate? Why take your biggest risks with your WORST cards (opening bats) against SA's strength (fast bowlers). Playing to your own teams & players ability to BLUNT the SA attack (a reasonable goal) & set up the game on a course Pakistan can control to see your own strengths magnified- best players in the middle order vs an older ball & bowlers not running rampant, freedom to play shots not forced to rebuild a shattered innings.
I think he played the right knock- Babar & Shadab were not forced to do any craziness, the task he left them was simply to go at a run a ball or slight acceleration. A SR of 110 asked of the lower order finisher is reasonable.
He played his role, Babar is the class player & he played with aplomb and simply had to tick at 6 an over= that's simply expected in ODI for your key players. Shadab wasn't asked to belt everything in sight to the fence, simply to go at about 7 an over. A boundary an over= again the most minimal pressure you expect to face batting in the last 10 overs vs a decent score.
Iman is not the superstar of the team. But an opener who can play their role is doing a valuable job. Fakhar is being selected as the aggressive one, Iman is being asked to anchor. It is a role suited to his abilities and if he plays his role, it allows others to do theirs. He probably won't win you many ODI on his own. But he can be the basis for victories as a solid role player.