"df" reveals that this directory -- and some others -- is/are actually a mount point for "aegisfs". If one were super-interested in the contents, I suppose editing mtab to change permissions (then restarting) might help.

Of course, if one does manage to gain write access and mess around with the aegis directories one might kill one's phone and need to reflash . . . so proceed with caution -- it probably won't be nearly as interesting as you're hoping it is.