So, when Gregory got in the head of the dead boy’s father and encouraged him to seek revenge on Maggie, she didn’t have a hole lot of restraint.
She was being blamed at Hilltop for sharing food with the Saviors, as if everything else wasn’t enough.
Not everybody is happy with Maggie.
Although she successfully got rid of him — and therefore enabled viewers to stop wondering when somebody was finally going to snap and just kill Gregory — by hanging him, his influence remains.