I guess beggars can't be choosers
Donating the food, as opposed to destroying it, was the first thing that crossed my mind when the scandal emerged. But how can they, when they can't prove its provenance is fit for human consumption? What if the "horse" (let's face it, it could be anything) was treated with antibiotics which made a human sick? Rolling the dice with human health is not cool, even for charitable purposes.
How can you say with such certainty that they can't? And even if they can't, you have to realize this. The homeless are not idiots. Wouldn't the ethical thing to do be to give them the facts, possible effects, etc. then let them decide? They're not animals, we shouldn't talk about whether or not to give them food like we're above them.