You might as well combine the Simple Lighting into the rule. Like this:
Trigger Event: Pantry door *changes*
Actions:
IF(Pantry door open) THEN
On: Pantry light
Off: Pantry light delayed by 15:00 cancelable
ELSE
Off: Pantry light
Cancel delayed actions
END-IF
This will turn on the pantry light when the door opens, and turn it off when the door closes, just like your Simple Lighting rule. If the door is left open, the light will turn off after 15 minutes. If the door closes during that 15 minutes, it will turn off the light, and cancel the delayed off.
Only problem is getting the light back on if the door has been left open for more than 15 minutes.