Former India star had signalled Chris Jordan for a short run - not grounding his bat inside the crease when running between the wickets.
TV replays showed Jordan's bat was in the crease. But nothing could be done as the third umpire does not the have authority to overturn an on-field call, unless it is referred for review.
In the super over, South African quick Kagiso Rabada struck twice to limit Punjab to just two runs, a total that Delhi overhauled in just three balls.
As social media erupted over the short-run decision, Sehwag tweeted: "I don't agree with the man of the match choice. The umpire who gave this short run should have been man of the match.
"Short Run nahin tha (It wasn't a short run). And that was the difference."
Cricketer-turned-commentator Aakash Chopra posted: "One short that wasn't. Technology must take over in these cases... What if #KXIP don't make it to the final four by 2 points??"
Umpiring standards also came into question in last year's IPL, during which India captain Virat Kohli tersely commented: "We are not playing club cricket."
Kohli's team Royal Challengers Bangalore were denied a win when the umpires missed a clear no-ball by the Mumbai Indians' Lasith Malinga on the final delivery.
The world's richest T20 league is being played in the United Arab Emirates after being shifted out of India due to rising coronavirus cases.