On a fresh install of great Nexcloud 18.0.2 
I share a folder with default rw access rights (Modify / Create / Suppress checked).
Target user can rename the share mounting point: expected behavior.
I share a folder with ro access rights (nothing checked).
Target user can NOT rename the share mounting point: not expected behavior.
I would expect that user receiving the share can not modify any content in the share, but can mount it where he wants.
Editing oc_table, field file_target does the trick: mounting point can be modify, the share remains ro.
Thx