Right. The button is just a way to terminate the DCFC session from the car side. You can also terminate the session from the charger side. But the button doesn't do anything for level 2 charging.You don't even "have" to do that. If you stop the session on the charger or via the charger's app, the Mach-E will unlock the connector and you can press and release just like with AC.
Actually No.Actually I think the manual specifies to press that button BEFORE removing the plug. Page 162 specifically says to press the button when stopping ac charging