The "disableautosave" CVAR has three possible values - "0" (off), "1" (only if levels requests it), and "2" (never).
However, the autosave setting in the misc options menu offers only two options - "on" and "off." Of course, the CVAR can be set to "2" manually, from the console. Then, the menu setting changes to "unknown"
I suppose it would be good to include all three options in the menu. This is not something urgent, just a convenience change.