The problem there, as I see it, is that it's the one good(ish) chess move (they) have on Trump.
They have been almost goading him to take hard all encompassing Federal action on the riots (kinda why Biden would again goad him). Yet as soon as he'd do it, it'd be "Trump shows his Dictator Aspirations. Walks all over State autonomy. Uses Military against The People.
And when Trump holds back….. "You did nothing!"
They kinda have him trapped somewhat on this one for the time being at least.