Keeping perspective
Trying to keep some perspective...
Just for the search on the East side of Pensinsular Malaysia, at the quoted 100km radius search range from IGARI, spotting a seat cushion is the rough equivalent of spotting a grain of caster sugar in Central Park.
MH seats are often blue (not always - I have no idea for this a/c), so consider the sugar in Central Park might be colored green or brown to get this in some perspective of what the SAR guys are looking for.
Even assuming there are a couple of hundred seat cushions and similar size debris, that's a spilled packet of sugar in Central Park, and quite spread out after a couple of days of drifting.