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It is a choice to decide on the delay between shutter button being pressed and the shutter being released. You can select the delay and it would function similar to using a self-timer to prevent camera shake.
No, what you've described is "antishock" in Olympus parlance. What's being discussed here is "release lag-time", which is different. Antishock adds a configurable amount of delay between pressing the shutter release and the shot being taken similar to a self-timer. Release lag-time allows the user to select from "normal" (default) and "short". In Short mode I believe the shutter curtain is cranked (for lack of a more accurate term due to my ignorance) and ready to go, held in place by something extra compared to the usual mechanism. You can hear this as a thunk in the camera when you switch to Short and exit out of the menu to go back to shooting. This is in contrast to Normal where the curtain is cranked at the time of shutter button press and then it moves. That's how the Short mode has less lag. It basically makes the shutter response go from fast to faster, not fast to slow like antishock does.
Here's a good discussion on what it does along with some sound recordings that show how the shutter noise changes when switching from Normal to Short.
What it does (speculation):
How it sounds (not speculation):