I don't understand why the Archdiocese of Chicago tolerates him. I believe the late Cardinal Francis George suspended briefly from his pastorate a couple of times, but he has never been effectively disciplined, let alone transferred or laicized.
I think it's fair to say that the present Archbishop of Chicago, Blaise Cupich, doesn't really give a flip that heretics control whole parishes in Chicago.
Perhaps we ought to keep in mind that a Fr. Pfleger's foster son was killed by random gunfire in the street maybe 15-20 years ago. That may explain his stance against guns. He has principally campaigned against violence in the high-crime neighborhoods of Chicago, tried to drive drug dealers, gangs, and pimps out of the area, forcefully criticized gangsta rappers who glorify street crime and the sexual abuse of women ("hos" and "bitches"), and worked hard to clean up his own neighborhood.
The link above gives a lot more background.
Why doesn’t the pope just fire the guy??
Pfleger has established a power base at Saint Sabina, one of the most active and most prominent black Catholic parishes in the city.
Normal diocesan policy is to rotate pastors every five - ten years, partly to prevent individual priests from developing “cults of personality”, in which the loyalty of the parishioners is focused on the man, not the Word of God. That’s exactly what happened at Sabina.
I don’t know how many decades Pfleger has had the run of that parish. Extending his stay early on was probably defensible - he was and is very dedicated to his black parishioners, if in a somewhat messed up way. But the longer he stayed, the harder it became to move him. I’m certain Cardinal George would’ve replaced him in a heartbeat, but the racial tension that move would have engendered was probably judged to be too great a price to pay.
The archdiocese continues to pay for a mistake made decades ago - not cycling Pfleger through the system before it became too late.
The Church tolerates him because his is one of the few parishes that operates in the black (pun unintended).