Roof wasn't taken to Burger King on his way to jail as some sort of special treatment or implicit approval of what he did. Shortly after his arrest and while he was being held in an upstairs conference room for questioning, it was determined that he likely hadn't eaten in a couple of days and they had no facilities for feeding him where he was being held. It's illegal to withhold sleep, bathroom privileges, food, water, or medical treatment from a suspect, regardless of the crime they're charged with. Someone was simply sent out to get him a meal at a nearby Burger King. This all comes from Snopes.com, who tend to be rather liberal. Even they said there was nothing to it other than just providing an arrestee with a meal.
from
Did Police Take Dylann Roof to Burger King? | Snopes.com
Regardless of all the straightforward reasons why police would provide food to a suspect in their custody, the plain
explanation is that Roof hadn’t eaten in days, and the Shelby PD didn’t have the facilities to house him and provide him with meals while waiting for federal and Charleston authorities to arrive, so they had to dispatch someone to a nearby business to pick up some food for him:
With the department’s phone ringing nonstop in the background, the young suspect with the bowl-cut hair was locked away in a second-floor conference room with an officer watching over him.
“Organized chaos,” Ledford later called it. “Because there were so many moving parts.”
Including feeding the unexpected arrestee.
“He hadn’t eaten, they said, in a couple of days,” [Pastor Strickland] Maddox said. “They bought him a hamburger. They just sent out for it. I guess one of the police officers went and picked it up.”
Ledford confirmed that this purchase was made.
“He did have something to eat while he was there, and he was secured in cuffs the entire time,” the chief said.
No reasonable reading of Shelby Police Chief Jeff Ledford’s accounts would suggest that Roof had actually been “taken to Burger King” after he was apprehended.