I'm confused, I took a brief look at both of those articles and they don't seem like a "failed shitstorm". Sure, there are points to improve, but it doesn't seem terribly bad. Which one is supposed to be the "failed shitstorm" and why? (I've been called an SJW before, so I might have some left-leaning bias here)

But those articles are irrelevant to the discussion. I've contributed to Wikipedia for years and I've got a good idea of how to add things from a neutral and objective point of view. My point is exactly that the existing article is not objective. For example, pretend the article of the Charleston white supremacist mass murderer said the following:

"Roof was involved in the controversy of the events of June 17, 2015. After a flurry of media attention, he became the lead defendant in the trial United States v. Roof (2:15-cr-00472), which was noted for the request for a bench trial..."

The above is entirely correct, and written in a neutral, flat tone, but it completely misrepresents the situation. By noting tiny, irrelevant details like the request for a bench trial and the criminal number, the article both becomes uninteresting and hides the truth. If you read the snippet you wouldn't get the idea that he was a mass murderer.

The same thing applies to the article about George Beto. He was objectively a monster. He used prisoners as literal cotton picking slaves, he operated a system that forced prisoners to mutilate themselves, and his direct subordinates shot people for no reason and let them bleed to death in an occupied dining hall "as examples". These things are not speculation, they're not partisan comments on Twitter, they're not even reporting in a possibly-biased newspaper - they're proven facts that were litigated to the highest courts of the land! These things are not even buried in court documents from decades back, they've been reported on and published! There is no reason for them to not be on Wikipedia.

Meanwhile, his page is about as dry and non-negative as it possibly could be. It reads like intentionally obfuscated, reputation-managed doublespeak, and only makes reference to some of the things he was convicted of in vague ways. It's a tragedy.

Then find sources that say as much and paraphrase from them with citations.

How do you add "Beto was a sadistic monster" and have it seem neutral? Factual and objective, but I'm sure it would not be accepted.

You gather addition fact based sources to cite.