It's the wrong play. The clock is more important than the TD here. If you score on that play you give Mahomes the ball back with 1:55 left and 2 TOs.
The pass to Diggs was it. You take the easy first and keep burning clock. You need KC to burn both their TOs and have about a minute left. Allen is the best when he takes what the defense gives him and that was the right play.... not the long TD.