it didn't get overturned because i think vermiel and his staff challenged the wrong thing. or, they challenged the right thing and the ref interpreted it wrong. i think the ref went over and vermiel challenged that the minn guy was out of bounds. the ref then said "kansas city is challing the ruling on the field that the player was in bounds". he then looked at kennisson on the replay (who was not even close to being out of bounds), ruled that kennisson was in bounds, and the play was upheld. he can't go under the hood to review what was challenged, see something else, and say "oops", that wouldn't be fair to the other team. but i think he misinterpreted vermiel in the first place, otherwise the guy who told vermiel to challenge that kennisson was out of bounds should be fired.
btw, this is from an avid chiefs fan in case it matters. sure it was 45-20 in the end, but that play was pretty damn huge. kc had the ball inside the 20 which has been almost a guaranteed td for them this year. that would have made it 14-7 i believe, maybe 7-7. it probably would have been no worse than 21-7 at half. that changes the whole complexity of the game right there.