I'm with Whip!!! Help that man recover "something" from his investment.
Yes, feathers dry out with time, but depending on the typical humidity of the area, they will only dry "so much" and stabilize.
The only real threat to them is mites and those can be dealt with by moth balls, cedar chips (pet bedding) or even freezing.
Look the feathers over good. If they have been chewed on by mites, it will be visible. Never store feathers with evidence of mites with sound feathers to avoid transfer.
I like cedar scented mothballs. They are in all of my feather tubs I don't worry about my cache of gray bars.