The paradoxical nature is that being homeless and starving is horrifying but something humans have become accustomed to, and yet the idea of selling organs is embedded culturally as being shocking, even if the end result of being starving and homeless is relatively equivalent to being desperate enough to sell organs, so it's not allowed.
Also, how you mention as fact that money from selling organs won't prevent long term starvation and homelessness is surprising; you don't know that's the case one way or another but you're trying to pass off an opinion as fact. I can't argue either that it would help with a clear and definite metric, but the correlation of living conditions and money is clear. How real-life application of such legalization or organ selling, with quality of surgery and post-surgery care, legal predatory practices, and other factors are dealt with are potential problems, but those are issues that exist in all commercial domains.
I also never argued organ selling as a solution to a problem; as others mentioned, it is a potential band-aid to a problem that lies in wealth inequalities, but which I find interesting as a societal flashpoint that show how knee-jerk emotional responses can cause logical paradoxes.