This wall segment seems to be roughly parallel to wall 6230 in room G-8, which is also on an irregular angle and does not have a clear relationship with anything else in the area. It is possible that it was never a true wall but simply a foundation for a feature, whose remnants are the opus signinum surface (6203) above.
Photo from east
Photo from east, close up of cuniculi
Photo from north in room G-9
Room G-8 central portion