They posed no threat to Ink. No point in killing them when allowing them to live serves a better purpose.
CJ was cornered in
Dunbar's basement armory, holding off zombies when Ink said "Leave her." He realized she was alone, and pinned. The rest of
the tower has fallen, there was no point in forcing her to come out and loose more of his forces, so he left her in her hole. No threat.
Duncan (
skittles) had a mental breakdown and hid. No threat.
Riley and
Kalani at
the hospital posed no threat either. He laughed when Riley drew her bow, and caught the arrow easily. They ran. No threat.
Puck had compound fractures in his arm and leg, as well as a concussion. He probably LOOKED one step away from dead, but either way, he was neutralized. No threat.
All of these people were able to then tell their story, and pass along the terror and expand on the myth of "The Man in the Pinstriped Suit," "The One With The Markings," "the colored one," and "Ink."
This is Psychological warfare 101.
What you have to remember is, while ink may have managed to get a good lawyer to get an insanity plea at his trial....He is NOT crazy.
"He knows exactly what he is doing."