So, you actually have three issues?
1- Default pictures directory as set by XDG_PICTURES_DIR isn't being used by the screensaver 2- screensaver's --location should accept ~/Pictures 3- screensaver doesn't work with pictures directory specified on an NFS mount point
So, you actually have three issues?
1- Default pictures directory as set by XDG_PICTURES_DIR isn't being used by the screensaver
2- screensaver's --location should accept ~/Pictures
3- screensaver doesn't work with pictures directory specified on an NFS mount point