I certainly agree that the NG troops -- and everybody else in a uniform on the ground there -- are in a really difficult situation.
But I'm not entirely with you on the other things. For one thing, in a situation like this, how exactly is anybody supposed to delineate between peaceful protesters and rioters? That seems virtually impossible to do in these circumstances -- unless the peaceful people and the unruly people make a concerted effort to stay apart from each other. And they almost never do that.
And none of this would've happened had it not been for people deliberately trying to impede and obstruct the operations. I hate to go with the whole "They started it!" defense...but it's true. That's what started all of this -- and it escalated not when the NG was called in, but when people started attacking the federal officers with rocks and such.
Given that, it would be incredibly irresponsible not to increase the engagement in order to keep those people safe and quell the unrest. If you want to call that "escalation", I guess that's fine. But it certainly wasn't unwarranted, given what was happening.