Virat Kohli is a very good player, but not a good captain. I would rather agree with Cricinfo's choice of Kieron Pollard. His win percentage in matches which he captained Mumbai Indians is quite high. MS Dhoni hasn't performed very well as a player in IPL 2021, but I would still rate him as one of the best captains. Steve Smith may be another option, but right now I can't consider too many other players for that role. As far as I am concerned, it has to be either Pollard or Dhoni.
I will choose Dhoni as a captain in any situation because he always finds a way to win matches and in the last season they had the worst team and yet the team was able to lift themselves in the later part of the tournament after the knockout stage defeating top teams and Mumbai is always a much better team and anyone can become the best captain with a good win percentage with a team like Mumbai who has dominating bowlers and a blend of local talents who could take on any bowler.