a quote from the documentation: Scans any new or modified files that you save to disk. If this option is deselected, it ignores new file installations (however, it will still alert you if a threat tries to launch). I would take this to mean you are still protected because WSA would still stop the malicious payload when it tried to launch.
I was tempted to say: Nooooo! Don't do it! That's where the secret is hidden! Oh gods, the doom you shall inflict upon us all would be unimaginable. Flaming scones would rain from the sky and a plague of ravenous ice cream monsters would take over London. Then I decided not to. Wait... I did... ._. Okay, anyway... Normally the client scans things on a delay on write. Minimal to no system impact. But, if you uncheck that, the check box will go away. If you save settings thereafter, it won't scan under those conditions anymore.