I don't know, I didn't investigate that much. I was running patrol missions with a friend for a bounty. I had never actually even seen the area before (although according to other people's comments it has always existed). I told him to meet up with me to see if he'd ever been here before. He said he'd never seen it before and pointed out the flag to me and claimed he'd seen it used to denote the starting point of strikes/raid. I suggested that maybe it has to do with the DLC, and that's about all I know of it.