People don't base this opinion on a single article but on the coverage of the situation holistically as it evolves. Most of the 'bombshell' revelations in this trial have been available on the internet since the week of the shooting. The number of videos and images that show that it wasn't until Grosskreutz pointed his gun at Rittenhouse and advanced on him aiming at his head that he was shot is overwhelming and yet it seemed to catch the prosecutors and journalists completely by surprise.

If you watch the videos of the event in sequence you realise that this is one of the most blatant and well documented cases of self-defence in history, yet people who have only consumed media coverage of the shooting have been surprised by the difficulty that the prosecution have had proving it was murder. Clearly there is something broken in the transmission of information there.

One thing that was the primary influence of whether this was actually self defense or not was what happened between the interview where he explained how and why he was there, to the start of the video in front of the store where he first fires. I'm not sure (I haven't been following the trial) - but have seen a few people mention that someone else "shot into the sky" while a fire was being put out, and words were exchanged, which led to the accused leaving the area, going to a better lit area, which is when the infamous video started.

It really puts a different perspective on the entire thing, especially if you notice at the end of the video he was moving toward law enforcement the whole time.

Yes, Ziminski shot a pistol into the air. Is charged with arson (but, oddly, not with shooting that gun) and was not called to the stand, there was a fight over that in closing arguments (both for defense, then for prosecution, then going to the judge to settle the dispute).

Rosenbaum is the one that threatened Kyle previously. It's not clear how they're related, but Rosenbaum and Ziminski were together in photos where a lot of the stuff was going down, this was referenced by the defense a lot in their closing arguments.