That is just it. John Brown's crime was against the United States of America as a whole not just against the southern people. And while Brown was hung for his crime there was no effort to root out those who supported Brown like the Massechusettes 6, or Frederick Douglas who had prior knowledge of the plans for the raid and said nothing, or Harriet Tubman who supposedly was to be at Harpers Ferry with Brown the night of the raid but reportedly was sick at the time. Supposedly she also would have had prior knowledge as did Douglas if she was supposed to be in on the raid herself.
Why were these people not jailed and possible hung also as accomplices for conspiracy to commit an act of treason?