No, it does deserve the vitriol. The South is not inherently bad and needs a better thing to rally around. The battle flag of a treasonous rebellion fighting to continue to exploit and harm an entire race of people for monetary gain shouldn't be it.

Stating a fact isn't the same thing as demonizing.

The Confederate flag represents a group of proud racists.

The cornerstone address literally contains "Our new government is founded upon exactly the opposite idea; its foundations are laid, its corner- stone rests upon the great truth, that the negro is not equal to the white man; that slavery — subordination to the superior race — is his natural and normal condition. This, our new government, is the first, in the history of the world, based upon this great physical, philosophical, and moral truth."

Read it for yourself:
https://www.owleyes.org/text/the-cornerstone-speech/read/text-of-stephenss-speech

You should know better.