Did you ever read about the incident? IIRC, the protestors were given the choice of going to jail or being sprayed or some such.
If it is warranted to take them to jail, then take them to jail. If it isn’t keep them there for a bit and release them. I’m sure the IDs could be recorded and repeat offenses judged on that.
To see them on the ground clearly not a threat, and this guy walking down the line spraying them, not really buying it.