they didn't say they wouldn't give you a receipt--only that the dollar amount of the donation would probably not be worth much as a tax deduction really, or at least this is the way I read it. i'm sure if you donated say, a truckload of materials --like a truckload of type 55 with an expiration date this year--that you could get a receipt. But a 20 yr old roll of exposed kodacolor II, probably isn't worth much. I might send them some old film we have lying around, if someone wants to actively collect what would otherwise be thrown away, more power to 'em.
btw--from working at a museum that takes donations...the value of the item is determined either by an independent appraisal on the donor's end, or by the donor (and their accountant). The institution doesn't make that call, but there's a limit to the amount you can claim for a deduction, up to a certain amount before needing the appraisal. I've donated one or two items in the past, and didn't write them off, only because they were worth like, less than 5 bucks on the open market, but they were something that was needed and wound up being displayed actually. I did it because I wanted to, not because I wanted anything in return.