What are they there to "assist" with?

The reason the State Police are so valuable (in the mayor's estimation) in policing the French Quarter is they are allowed to get away with more.

But the proceedings opened a window into the disparate rule books governing the State Police and the New Orleans Police Department. The NOPD is subject to a strict federal consent decree that forbids racial profiling and allows officers to make investigatory stops only when they have "reasonable suspicion that a person has been, is, or is about to be engaged in the commission of a crime."

The State Police began patrolling the French Quarter on a regular basis in 2014 following a high-profile shooting on Bourbon Street that killed one woman and wounded nine people. Since then, troopers have assisted the NOPD in seizing weapons and drugs and investigated a host of other crimes at a time when the NOPD has struggled to recruit new officers.

"We were never told not to do our job," Edmonson said in a recent deposition. City officials, he added, "clearly knew what we brought to the table" when they requested assistance patrolling the French Quarter. 

There is an expectation right now that the NOPD consent decree may be coming to an end soon. At which time they can go back to doing their own bullying and harassing of citizens without consequence and the State Police "assistance" is likely to end.