Sorry, but there is no way to script a delay on counting an objective as complete.
The engine does not depend on a script to count the player walking into the zone as a completed objective, it does this seperately, and as such you cannot script a delay in the end of the level like this.
One work around you could try is to spawn an objective item above the zone and zone delays the spawning of the item.
And no need to apologize for asking a question. We all have questions at some point and usually more than one person would like to know an answer to it.
The one and only,
~PlystirE~
Urlforce:
Dude, I'd rather be declared a dbpro noob than an fpsc legend any day!