Since safe mode is in general resulted from any sort of crash in previous session, it is not in principle intended for operation use, the main objective is to raise the operating system by making available most of its resources and configuration tools that are graphical, since Windows is a GUI based OS, and then rerpair currupted files when applicable. The idea of operating Altium Designer (or any other software) in such a way is something so obviously unusual that even its manufacturers should not have foreseen state such restriction in the system requirements list.