Sm29, the people who did that were unmannered louts, completely lacking in common decency. If someone gives you a sincere gift, especially one for that purpose, it’s the depth of bad behavior. They might as well have slapped the givers in the face and spit in their eye. And it’s a waste of perfectly good food.
I’ve been given treif food by ignorant but well-meaning friends. I thank them sincerely and quietly pass it on to a needy Gentile later. That is the only proper response. I might explain later that while I thank them for their kindness my religion has a number of restrictions which don’t allow me to eat it, even though it looks and smells delicious.