because they are desperate, and this is a charity fundraiser instead of a giveaway.

say you have 1,000 t-shirst with your company's name on it, and it's a name that people like; you have the shirts because your company wanted to sell them, but no one really bought them or didn't buy enough, so you say fuck it and give them away for free since it puts your name out there as marketing ... that is not a charitable donation.

however is you were to give them away to someone else who is looking for shit to sell to raise funds for a charity, you yourself would be supporting them in supporting a charity since they wouldn't have anything to sell without you giving them 1,000 t-shirts (that you had to pay to get made) .... even if the shirts are essentially worthless to you and a market failure, it's still being donated to raise money for a charity.

from a tax perspective HIB is probably something of a Non-profit corporation that specializes in running fundraisers for Childsplay and the EFF, the products they sell to raise funds for said charities would then technically be donated to them to sell for said charities. EFF & CP get the money that is attributed to them, HIB gets their tip, and the publishers subtract what they get from the calculated tax write off of donating the games at market value.