Not quite. You also need to be holding the control stick down to trigger an auto-landing. But even then, that can be aborted and the auto landing immediately cancelled if you just push the control stick back up.
There is no logical mechanism...
I’ve flown a drone above water since I bought a Mavic Pro when they first came out. Sea, sea loch, loch, lake, river and stream. Still got the Mavic Pro which has never needed any repair other than propeller blades which are disposable parts...