Not what it says. It says that if there is an "extraordinary emergency" then trump can take resources from the DC police for 48 hours, but then has to give written proof to Congress that there has been an extraordinary emergency. With that written proof he can get 30 more days, but then needs Congress to actually grant more time.
So let's start with whether there has been an "extraordinary emergency." DC does not seem different when trump declared the "extraordinary emergency", so it was not "extraordinary", nor much of an emergency.
Moving on, has trump provided written proof to Congress? No, so the next 30 days are arguably illegal too.
But all this is subjective. Which is to say it is neither 100% legal, nor 100% illegal.