I have given this a little more thought and I can see both arguments. Steele was not good at LT, but it was his first game playing there. Maybe he learned something from that game and will be better next week. The Falcons have only 11 sacks this season. They are near the bottom of the league. Maybe this is the game for Steele to find himself at LT.
On the other hand, Maybe it made more sense for the Cowboys to stick with their plan. Steele is the RT and Nsekhe is the backup LT. The question is who are the 5 best? Maybe Nsekhe, Collins, Biadasz, Martin and Steele are the 5 best. And when Tryon comes back, He simply plugs in at LT.
At the same time, this team was 6-1 with Tyron, Williams, Biadasz, Martin and Steele.