to be fair MOVE was basically a cult and had done a lot of nutty things over like a 15 year period beforehand, like changing everyone's last name to "Africa" and living in extreme squalor with many children; as well, everyone was taught that John Africa was their father and that they had all been reborn and were only 1 years old for some reason
that being said, the Philly government was (and probably still is to some degree) insanely racist, and spent much of its police force attacking anyone it considered an "outsider", such as black people, liberals, lgbt community, etc
the previous mayor frank rizzo was both police commissioner and mayor for over 20 years and still had quite a bit of influence up until the early 90s when he finally died, and he was an incredible racist, sexist, homophobic, etc