This Navy vet joined the protest in Portland because of the danger inherent associated with federal agents with combat fatigues with no insignia hauling people off the streets into unmarked vans. I.e., if they can do, so can anyone: just buy a used uniform and go for it.
I don’t carry a gun, but if I did and such a person grabbed me, I have to think, if I were physically able, I would instinctively put a bullet in his chest, and let him bleed on the sidewalk while I called 911 to report the incident.
This is one of the reasons that the local police are a much better choice to contain any criminality that may be connected with the protests.
Also, the police of any city in America would far rather handle this themselves, which I happen to know for a fact via my connections to the Philadelphia Police Department.