Homelessness should never be tolerated in any society and if we start designing in to accommodate homeless then we have totally failed as a society. Close proximity to homelessness unfortunately makes us uncomfortable so perhaps it is good that we feel that and recognise homelessness as a problem rather than design to accommodate it.
You would think designers who create street furniture that prevents people from doing certain things, like sleep on them or skate on them, are unsympathetic bastards. But judging by this interview that is not necessarily always the case.
And anyway, I believe we do need constraints in our public spaces because not all of us (or maybe even none of us) are capable of living well together in an absolutely free environment (as if such a thing would exist in the first place).