It’s like Worf’s sash or Ro’s earring: it’s entirely related to their native culture and has absolutely nothing to do with Starfleet. They were just given the clearance to wear it as part of their uniform on the grounds of that item being culturally significant to their species. The fact that this sash happens to be colored similar to one of the three standard Starfleet colors is entirely coincidental and entirely unrelated to their division, rank, or anything.