After killing the serial killer, Keith had already vented his anger at being disturbed from his sleep.
Some onlookers were hiding at McDowell's or their houses as they peered through the glass windows and witnessed Keith's killing. Surprisingly, none of them were hypocritical enough to condemn Keith for killing the serial killer.
After all, those hypocrites had either died or were the ones who fled first. Not to mention, even if Keith killed someone in a public place, none of them would think that Keith was at fault.
As for why it was because Keith's reputation was tantamount to being hailed as the messiah. His reputation had already surpassed the son of god since compared to that fictional character, Keith existed and helped those who were in need.
Even those who were religious had started to waver in their faith and beliefs toward god. After all, they kept on praying and waiting for god's miracle yet nothing solved their problems.