What evidence would you cite to defend Papa's actions in chapters 11 and 12 of Roll of Thunder, Hear My Cry by Mildred Taylor?

In Chapter 11, T.J. shows up at the Logans' house and tells them he's been badly hurt. R.W. and Melvin Simms tricked him into robbing Mr. Barnett's store in Strawberry. The Simms brothers wore masks during the robbery, and R.W. hit Mr. Barnett with the flat part of an axe. They left Mr. Barnett on the floor; Mrs. Barnett also fell in a scuffle. When T.J. wanted to tell the authorities what happened, the Simms brothers beat him badly. After Stacey and the other Logan children return T.J. to his house, they see a white mob show up. The mob includes the Simms brothers, who tell people T.J. was responsible for hurting the Barnetts, although in reality they were. The mob enters the Avery house with violence:

Soon, the front door was flung open from the inside and Mr. and Mrs. Avery were dragged savagely by their feet from the house. The Avery girls were thrown through the open windows. The older girls, attempting to gather the younger children to them, were slapped back and spat upon. Then quiet, gentle Claude was hauled out, knocked to the ground and kicked.

The mob is bent on violence, though Mr. Jamison tries to convince them to let the authorities deal with T.J. When the Logan children go home to tell their parents what happened, Papa leaves with his gun. Mama says Harlan Granger will stop the white mob, but Papa says Harlan would have already done so if that was his intent. 

Suddenly, a fire breaks out in the cotton fields. Both black and white men, including those who were in the mob, work together to put out the fire. At the same time, T.J. is transported to jail. It is clear Papa started the fire to distract the white mob from hurting T.J.'s family. Although this is a criminal act, it is defensible because Papa knew the mob might kill or hurt T.J. and his family. The men in the mob mentioned the ropes they had, so they were clearly thinking about lynching the Avery family. Papa knows about other events in the community, such as the burning of the house belonging to the Berrys in Chapter 1, that show a white mob can be deadly and destructive. Additionally, he knew that men like Harlan Granger, who might've stopped the mob, had not done so. Also, Papa started the fire on his own land, not anyone else's, so the fire he started only hurt his land. Finally, the fire achieved what he wanted—an avoidance of the worst kind of vigilante justice.