The other side of the coin is "Why not shut down?"
If you are not trained and have not done an idling dismount, then do not learn the trick when you are already a bit embarassed and flumuxed with an off site landing/door unlatched incident. Those extra distractors are the signs that you must now watch yourself very carefully. A real pro learns the way to tell himself NO as he sees these tiny hairs rise on his neck. Unusual things are to be carefully watched, and corners that you get jammed into are dangerous corners, indeed.
As long as the helo has been starting OK, just land, shut down, close the door (and look around at the whole helo, too) then climb in, restart and fly away. If you have regularly operated to idle and dismount, have a ball.