Your right, but OP was incorrect in using the word policing when the Act passed by congress actually uses the words "domestic" law enforcement; (imo) arguably this includes any action that stems from edit: ACTING ~~enforcing laws~~ on domestic, as opposed to foreign, soil. Further the exceptions allow for military to "provide" resources that support domestic enforcement officer which (again imo) would not extend to 'not providing/actually removing' resources that domestic enforcement officers do already have..
All that to say what the act does do is create a grey area that can be argued either way and which does force the federal government to have to think twice about using the military for such matters.. for better or for worse
Edit for clarity
Couldn't help looking it up - so satisfied that it's called a lounge of lizards