Antelope's video shows a fairly wide spread between ground searchers. Depending on color, shape and distance from searcher the smallest objects they can expect to find will be 4-6 inches.
Small fragments produced by a bomb going off nearby will tend to be much smaller and would likely blend in nicely with the pebbles and local soil.
To find those, you pretty much need a shoulder to shoulder search on hands and knees. Given the area, not really feasible. Perhaps such fragments may be found lodged in the airframe, baggage or bodies.
The local news made a big deal that an anonymous Egyptian expressed an opinion that likelihood of a bomb is considered 90%
The possibility of flutter is raising its head. Control surfaces parted company with the airframe. Whether that was the initial failure or came some milliseconds after something else remains open.