I do think Garth flubbed his lines as Prior had in mind a few times. I do not think he was supposed to say the raccoons were all buried in the compost area. I think he was supposed to say he saw them daytimes. I can't recall all, but I felt that there were several relatively minor points Garth flubbed. (Or rescued, if he was more honest than anticipated.)
But I think Prior was pleased to show that casting out evil spirits as in that story did not kill people like Emma or Newel Knight. His point was just calling people dark was not a kiss of death. It's a weak argument, though. Just because Emma and Newel continued on, it doesn't change that the murders for which Chad is charged did occur. And the belief system, that they were zombies or whatever, and castings were needed, isn't the illegal part. It was the actions taken to supplement the castings that caused death that were illegal.
MOO