Sitting him would do more harm at this point. He's coming off one of his worst games since he started playing in college. It's never just one player but he damned near brought the WFT back by himself.
I do not know the extent of that calf but the Cowboys are known for downplaying any injuries from way back. I did think it bothered him moving to his right and he was throwing high because he was not using his plant foot properly and using his arm too much. He is also not the type player to play the injury card as an excuse.
If it is that calf, chances are it is going to be a problem by the playoffs so the rest will not be as beneficial as him learning to play with it and overcome it.
The team has not given up on homefield and has a game against the team holding that right now. While it is doubtful they would unseat TB, they might get a more favorable matchup than the LAR because McVay loves him some playing the Cowboys.
As long as the team is playing for something, Prescott will not see the bench.