He was certainly an unusual person.
As Fredrick Douglass said, he could live his life to give freedom to the slave, but Brown was more committed, and he would die to give freedom to the slave.
The slave power was basded on the use of force, torture, occasional murder, and other forms of coercion. John Brown recognized that, and was willing to turn those methods against the slave power.
And for that, the slave power supporters will never forgive him. After all, they were special, entitled to use force to support slavery, and noone else was permitted to use their methods against them.
I didn’t know that the Virginia treason statute had a provision about alternative governments in it. I learn something from these threads.
But, why did they choose to charge Brown with treason when they could almost certainly hang him for a number of other crimes? One good reason probably concerned the powers of the governor at that time.. As Thomas Jefferson noted in his Notes on the State of Virginia:
"In every case however, except that of high treason, there resides in the governor a power of pardon. In high treason, the pardon can only flow from the general assembly."
One book that I read about Brown suggested that Brown was charged with treason to ensure that Governor Wise could not pardon Brown or commute his inevitable death sentence. Although he probably would not have been inclined to commute the sentence in any event, Governor Wise was planning on seeking the Democratic Party's presidential nomination in 1860 and maybe it was thought that he might try to use a commutation to advance his cause with Democratic delegates in the North. Who knows, but they weren't taking any chances and that's probably why they charged Brown with treason.