If you take the setting off 'A' (automatic) and just use it with manual settings, the battery isn't required and there is no interlock. And the truth is, if you don't have a 1.35-volt PX-625 mercury cell or equivalent in the battery compartment, your exposures are going to be off anyway, unless the meter has been readjusted for a different cell voltage.
You're right, though. It's a killer little rangefinder with a shutter that is quieter than a Leica. Or at least the Leicas I've heard. And because it's a leaf shutter, it flash-syncs at all speeds, making fill-in flash a comparative breeze to do on the fly.