I’m not even sure there was a point to the article other than an attempt to bash a dead man.
His most well-known run-in with the law was a 1977 attack on movie studio executive Shelly Saltman, whom the daredevil beat with a baseball bat in the parking lot of 20th Century Fox. Saltman promoted Knievel's infamous attempt to jump Idaho's Snake River Canyon and then wrote a book about the experience, angering Knievel by portraying him as "an alcoholic, a pill addict, an anti-Semite and an immoral person."
SEems pretty suggestive of a dark side to me, but perhaps our frames of reference are different, and drug and alcohol addicted people who assault others with a baseball bat are not expressing their "dark side".