The matter is of interest because a new feature about them, which 'of course' will address the concert. The initial press is not encouraging.
Of course, the project will include the 1969 Altamont concert in Northern California where the Hells Angels provided a barrier to make sure that the crowd didn’t come onto the stage when the Rolling Stones played. As the story goes, their “payment” was in beer. The Angels got into brawls with the fans and a pregnant woman ended up with a skull fracture and another young man was stabbed to death. It was total chaos. After that, the Hells Angels were persona non grata, and public opinion about the club changed for the worse.The woman was hit by a beer bottle thrown from the crowd, not by the Angels.
As for the other matter: 'A young man was stabbed to death.' True, as far as it goes.
Here's a documentary on the matter.
The young man in question had been thrown out of the concert for trying to climb onto the stage. He went somewhere and obtained a revolver, returned, drew the gun, and charged the stage again.
Another story built into the mind of the Boomer generation is the assassination of John Lennon. The Hells Angels stopped a similar attack on the Rolling Stones, perhaps the only band of equal stature to the Beatles.
The Angel who saved the Rolling Stones did it without shooting into the crowd, without hurting anyone else, and by charging a gun with a blade.
That's not bad. The failure to understand what they had seen right in front of their eyes was not the first such failure. We are still today living with the consequences of many other failures by just the same people, of just the same kind.