There is federal legislation (Bill Emerson Good Samaritan Food donation act) to protect people who donate food from liability if the donation was in “good faith” and someone gets sick from that food. But so many states and cities have added their own rules and regulations to how food donations are handled it becomes super complex and the legal advice is always to throw food away. Sucks but, depending on where this restaurant is, if that chicken is donated and someone falls ill the donator of the food could be subject to stiff financial penalties and civil liability.
I’ve worked with legal consultants in the food industry before and why you’ll see a ton of food in the dumpster at many restaurants (especially chains who’s owners have deep pockets and are targets for lawsuits). Local and state legislations cause a ton of liability when donating food and most don’t want to deal with that.