why do they still play on the radio when they hate him

They no longer hate on him after his death.
It's just like every valuable thing , wewe don't get to respect it when wewe have it and wewe do realize its importance once wewe don't have it anymore. But yeah , still some stupid people dislike him. Haters gonna hate wewe know. No matter what.
Even when he was alive , still his songs were being played on Radio I believe like "Heal The World" , "Billie Jean" etc. No matter how wewe look at him , turn a blind eye au not. wewe still can't deny his excellent music.
His muziki had great messages in it.
:D

Some people hate him and enjoy his music. One of my classmates hate him and talk bad about him but during our school's talent onyesha michael jackson's bad was played and he even sang and danced to it although he hates him.

Like i alisema michael is de king of pop but thy hate him