People don't respond to homelessness when they've convinced themselves that homeless people deserve it. "the world sucking is no reason for you to change your attitude one way or the other" is of course absurd. If the world sucks, there's a reason to change it.
Stereotype much?
"Deserve" is a loaded term.
Homelessness is often a consequence of choices made by the homeless person. For example, SF has both homeless and shelters that go unused. In other words, there are folks who prefer to be homeless to living in those shelters.
Is it really unreasonable/wrong/immoral for folks to respond with "okay - I've done enough" wrt those homeless? If it is U/W/I, what do you want said folks to do? Build nicer shelters? Force those homeless into the shelters? Be precise - what will it take for you to be happy with the response to those homeless?
The reason that I say that he's assuming (in most cases) is that people typically don't explain themselves, they just do.
More to the point, that sentence expresses a dissatisfaction with said "do", regardless of reason. Is it beyond the pale to question that dissatisfaction?