Maybe there's more to this story, and I'm not especially familiar with the Missouri law. But I'm inclined to side against the police in general, and especially in this case.
For sure, the motorcyclists are being pretty lax about obeying traffic law. You'd have to convince me that this isn't typical driving for the area though.
If you want to talk about hogging the road, check out this picture of typical Dallas traffic:
https://preview.tinyurl.com/yc5qv6fk But I guess that's cars? Do you think they're holding up traffic?
The most important thing about this, is that the police are COLLIDING WITH CIVILIANS on motorcycles over presumably traffic offenses. That's unacceptable.
In my opinion, they should be pulled over individually for individual offenses. If that's too onerous for the police, then that's so sad that law enforcement is harder when you live in a free state... which of course we don't.