I'm confused, where are you seeing this procedure that you can't set T/O flaps after being deiced? All I see is Vol 1 5.16.2.11 (Cold Weather After Landing Procedure) that says after prolonged operation in icing conditions with the flaps extended or when landing on a slushy/icy runway do not retract the flaps until the flaps have been checked to be free of contaminants. If you get to the gate and the flaps are contaminated just leave them down and whenever the next crew gets to the plane they will taxi out with the flaps down until getting deiced. A deicing spray down and contamination check satisfies the Vol 1 requirement and the flaps can then be set for takeoff.