I would think that Styrofoam and plastic would be easier to digest than flesh and bone, but IMO the discussion does not matter. Even though the engine may digest it, and keep running, there will be damage. And if there is damage there is a possibility that the engine could quit no matter that it usually keeps running. The "Miracle on the Hudson" was caused by a flock of geese with many birds stuffed into each engine. It is now possible to pilot a flock of UAV from one controller or transmitter. If we don't stop people from flying near full aircraft then maybe a flock of UAV's will bring down an airplane.