I completely get your point and you are right.

However, understand the context: the beggar entered a McDonald's and asked clients that were currently eating for money. He got offered the fries of a woman who didn't finish them. So there was no poisoning (I think this is very much an American problem, where I don't live) possible—except if you consider McDonald's to be poison in the first place.

In my experience, people don't give cash to beggars anymore. Everyone has their reason, but I think the fact that a lot of beggars were not really in need hasn't helped. But I think many would be open to give food or donate useful objects instead (which they don't have at hand when being begged).