Hi Guys,
Thanks for the bug report.
I was able to verify this bug and fix it. I've patched the 2.3.6.4 release, so if you download it again and replace the /bin/mojoPortal.Web.dll with the new one it should fix this problem. It is also fixed in the source code repository.
Note however, that the Administrators role is a special system role that can do anything, you cannot limit this role to draft edit permissions, you should use custom roles to limit users to draft permissions.
Best,
Joe