I don't think anyone is arguing that. "Throwing them on the streets" and "discouraging them from hanging out in the library unless they are actually using it" are two different things entirely.
No,I don't want homeless kids from being discouraged from hanging out in the library just because they stink and make rich people uncomfortable. Just because some folks don't acknowledge the dark side of the USA, where is little/no support for your fellow citizens who fall off the train, doesn't mean you can grind them down even more.