What happens if the session isn't SYSTEM and the user sets datastore['GETSYSTEM'] to false. I guess you would like to add a check to  exit the module in this situation. At the moment, what happens is what the module tries to continue even without SYSTEM and fails:

```
msf post(admin_me) > show options

Module options (post/windows/manage/admin_me):

   Name       Current Setting  Required  Description
   ----       ---------------  --------  -----------
   GETSYSTEM  true             yes       Attempt to get SYSTEM privilege on the target host.
   PASSWORD   password         yes       Password of the support user account
   SESSION                     yes       The session to run this module on.

msf post(admin_me) > set SESSION 1
SESSION => 1
msf post(admin_me) > set GETSYSTEM false
GETSYSTEM => false
msf post(admin_me) > rexploit
[*] Reloading module...

[*] Target OS is Windows XP (Build 2600, Service Pack 3).
[-] Couldn't access registry keys
[*] Post module execution completed

```