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.
In the world of every parade that has been performed in every major city for the last two centuries at least.
Ahhh, I’ll remember to drive right on into that parade next time they’ve moved off closed streets.
Nothing you say will stop the parts of this protest that are riding into oncoming traffic as safe. They clearly didn’t get coming traffic directed away.
The unsafe thing here is the driver who insisted on dangerous driving. Motorists have an obligation to not cause harm regardless of what others are doing.