They'd better fry that little shitbird. Having the state do it sends the message. If Roof gets life, and the white supremacist prisoners slip up for even a moment, Roof will catch it hard and fast, and that'll make his point for him.
On hearing that his mother had a heart attack when hearing the scope of what is happening, my first thought was not particularly empathetic. 22-year-old son, those are parents that had a chance to influence that boy for the better, and the magnitude to which they failed is astonishing.