a relatively small number of civilian criminals?
What is a small number of criminals, ten, twenty, less more? There were enough to wound 50 secret service agents not to mention the looting and fires. What is the alternative, open up with the 50s when they storm over the white house fences? Obviously the DC caretaker mayor is not going to do anything. They are spoiling for a scene, give em one. Millions for defense, not a penny for tribute.
a relatively small number of civilian criminals?
Relative to the population of Washington D.C., yes. I'm not suggesting that they roll over and do nothing about the looting and riots. But bringing in the regular military (not the National Guard) to deal with rioting civilians would be an unprecedented step of dubious constitutionality. These guys are trained to shoot first, ask questions later. Bring them in and the bodies are really going to start piling up, not just the rioters but also people who were just in the wrong place at the wrong time. The same training that is an asset on foreign battlefields is a liability when dealing with US civilians. In President Trump's words, "The cure cannot be worse than the disease."
ma duess would do just fine