Unless the troops are going there to shoot every looter and every rioter on sight then what will they do that the police and National Guard can’t?
What he said is that there are so many places that people are rioting that there aren’t enough police and NG to cover everything.
The US Military has the most advanced “active denial” capabilities on the planet. They are fully capable of dispersing unruly mobs using non-lethal means. Definitely unpleasant for those on the receiving end, but non-lethal.