Coff,
Precisely as you say, an anti FOD device. The slots for the power and condition levers were wide enough to allow all sorts of stuff through. If working on the overhead panel, for example, you dropped a screw that went through, the resulting FOD plod could keep you away from the bar for hours
I believe the Flt Eng usually removed it before and replaced it after flight when en route.
Smudge
