Reviewing that whole article from Rolling Stone, i'm surprised that folks would be citing it.  So much innuendo about how Andy Ngo had a meeting with the Proud Boys and trouble with his employer.  A reporter can't interview both sides, get diverse views at various gatherings ??? without drawing criticisms ???

Bottom line seems the article was strongly implying -- its OK to be beating up a reporter if he happens to be aligned with any groups on the right.  Implying its OK to pour or throw a milk shake over his head.  OK if its containing some substance like silly string, etc. The article confirms that the left wing group members, antifa did hit him.  

Other sources published photos of his injuries on the face.  He went to the Hospital Emergency Room.  And there were reports he had some diagnosis of brain bleeding.  Maybe those left wing articles say the brain stuff was only alleged.  Implying that beating up is OK if there's no brain bleeding???

Just one sentence in the article mentioned: "Footage also surfaced on Twitter of Ngo at the rally, being doused with a milkshake and silly string, and getting punched by an antifascist protester."   An effort to minimize, yet admitting an assault occurred.  Photos of the damage around his face & head tell a different story-  multiple marks can be seen, likely multiple blows.

Sorry,  but I'd still put this in the category among the few beatings the media has bothered to publicize.  Plenty of violence at those antifa mob events.  Even killings.