This was a Critical Mass event, which is why the bicyclists are taking up all of the street as a way to reclaim the streets and protest the lack of safety for riders under usual conditions. It’s not legal, but protests are never useful if they’re fully legal now, are they.
Do you also live somewhere that cars can legally cross a double yellow and travel in the wrong direction down the roadway?
Read the last line.
Misled by crappy title & description that didn’t mention cyclists riding the wrong way against opposing traffic, and a picture that didn’t clearly show cyclists doing that.
Fair enough.