Unfortunately this outcome wrt giving/receiving sometimes happens, both in and out of homeless communities.
Sometimes it is reasonably logical. For example if the recipient perceives that receiving the offer reflects well on the giver, and would therefore be an unfair way to paint the situation due to other factors. In such a case the unwillingness to receive is a reverse-judgment on the situation, or the giver, etc. This preserves what they feel is their right to act on an ethical outlook.
They may also see the outreach as a setup for a covert, unjustified condition which the giver is attempting to impose. And sometimes it appears to them that their tacit agreement is being bought, as to "which side" is winning an ongoing argument over worldview & lifestyle.
This is especially common among those who are protesting what they perceive as a voice teaching "the right way" to be a responsible person, etc. If their return message doesn't get across, they may attempt to expose the giving-side to whatever horrifies the giver most--drugs, homelessness, etc.
This is only one possibility though, and even then it's not necessarily a fully conscious decision on the part of the potential recipient.
I've also seen this happen among those leaving high-demand religions, when no homelessness is involved. Sometimes this is also discussed in post-religious communities along with concepts like "love bombing" which is seen as a common form of manipulation.
Giving/receiving across that line in the sand can get totally messed up and must sometimes be mediated in some way by relying on a third party to provide a more objectively acceptable form of care just by not being one of the regular parties to the situation.