It's not deleting the dumping stockpile that does it: it's removing the permissions to have corpses in a stockpile (which, if you've got a dumping stockpile set to allow rotting corpses, will solve the issue).
For me, the flickering persisted even when I deleted my dumping stockpile; only when I deleted both that and my fridge stockpile zone did the flickering cease. Re-adding the fridge zone with all the prior permissions started the flickering; disallowing all corpses solved the issue, but allowing even one type of corpse back in resumed the flickering.
For me, the flickering persisted even when I deleted my dumping stockpile; only when I deleted both that and my fridge stockpile zone did the flickering cease. Re-adding the fridge zone with all the prior permissions started the flickering; disallowing all corpses solved the issue, but allowing even one type of corpse back in resumed the flickering.