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.
Then she would have to pull over and wait 10-15 minutes for them to pass. Geez.
In an emergency there would be lights and ee-oo-ee-oo and the bikers would definitely part to let the emergency vehicle.