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.
Who’s to say that they’re not doing both?
I sometimes go on these critical mass rides and I am heavily involved in the local council meetings here when they discuss infrastructure. Unfortunately, you have to be squeaky wheel in order to get the grease.
Yeah, people are trying to get home etc. But it’s a minor inconvenience compared to cycling on bad infrastructure.