I can't believe we're still talking about this, but here's my 2 cents. The OT rule is what it is. Would Buffalo have scored if they had won the toss? Maybe, maybe not. They should have never been in that position had they handled the previous 13 seconds differently.
The Chiefs had to get enough yardage in that amount of time to kick the field goal that tied it up. All Buffalo had to do was hold them (literally) on the first play. It would have been a 5 yard penalty and taken time off the clock. They could have done it 3 times and the Chiefs would have only gotten 15 yards and time would have expired. Now, the game can't end on a defensive penalty, but they would have only been at their own 40 and had no choice but to throw a hail mary, and the odds of that are slim.