From the application,it is true that WOPEN=7 and WOPEN=8 does not work with the safe mode application.
In the code,it is implemented like this only that apart from WOPEN=0 and WOPEN=5 (0(stop) and 5(suspend) requires password),command type is WOPEN OTHER then it will throw error.
But in the rsponse of AT+WOPEN=? command,
Only 0 and 5 is considered to omit (as these require password) and range is upto 8…this may be because of range of mode available for AT+WOPEN command.