This strikes me as bait.
They would love nothing more than a group of angry counter protesters to show up. They know the heat is on and this might we'll be the final surge before they flame out. Nothing would be sweeter than if (God forbid) something deadly would occur. It would instantly be Trump to blame for the "peaceful" protesters dieing. The MSM would be showing crying parents and crisis actors a plenty. Blood on the Whitehouse lawn or there abouts.
Less than two months from the election it would sway many voters.
So again I think this is bait plain and simple.