If there is no evidence that the trusses were cut or modified than it is likely that they were designed for storage. I would put in my report that trusses are generally designed for dead loads only and recommend contacting the builder / truss manufacture to confirm that storage is permissible.
However, the bottom cord of the truss appears to be only 2x4 and even if it is 2x6. This means that under the OSB there will be either inadequate insulation, compressed insulation or (more likely) no insulation.
Lite storage on trusses never bothered me but when it affects the insulation you may be better off renting storage space.