former black panther mumia abu-jamal was hospitalized at schuykill medical center in pennsylvania on april 2 after collapsing in prison .
he was delivered ` get well ' letters from third graders in orange , new jersey , and high school students in the philadelphia student union .
the letters made mumia ` chuckle and smile '
critics say they ` promote a twisted agenda glorifying murder and hatred '
mumia is serving a life sentence after years of appeals won him a reprieve from his death sentence in 2012 .