Hi, don't want to get in the polemics that seems to be starting to get flaming, but notice that you don't need to abandon him or just call the cops to get to William's scene.
In one gameplay, I intervened, fought off the guys, even helped him, and still got the William part. What really makes the difference is if you help him only with one thing, or with both, when you are given the choice. And in one of the plays I honestly found not so strange that she helps him only for one thing, since she has to go back home and is in a certainly psychological sitaution. That is not being an "uncaring asshole", since she went when there was the noise, she went in to see what was happening despite knowing there were problems, than she still helped Bobo after.
When someone asks you for money to buy food, you can and buy the food with them, or you can just give them the money, but if it is true that the first thing is even nicer, doing the second does not make you an "uncaring asshole".
Plus, honestly, many, if not most, people would not care even about going to check the noise, and seeing trouble, would not call the police or even less intervene, especially, for this second option (intervening), if you consider that depending how you played/see her, at that point she may have already the profile of someone who would not defend herself.
So, definitively if you make her do that, she is already very far from being an "uncaring asshole"