I think you're onto something here.
If Bills win division they would have a home playoff game and be subject to bad weather. So snow, sleet, freezing rain, strong winds, you name it the Bills would be subject to it. Plus the enormous pressure of having to win the 1st playoff game.
I think we've clearly established at this point that the Bills are not built to play in bad weather.
Now as the wildcard they can travel to warm weather climates or even Indys dome where I would favor them to win. Plus no pressure to win the game as the wildcard. They would essentially be playing with house money.
Long term the wildcard is better