>>212363540He is mocking people who engage in virtue signaling and advocate for causes like aiding the hobo to gain a sense of moral superiority.
However, the point is that the cost, burdens, or repercussions of these causes are borne by somebody else, not themselves (or they might be unaware that these costs are affecting them, in such case they keep pushing).
Their support for the cause reduces when they begin to experience the drawbacks.
In this example, homelessness could be resolved if those promoting the cause, or even 10% of them, offered shelter to the homeless, but this is costly, risky, and even dangerous. Vooting for super-duper authority that takes resources from others to address the issue, is better, you can larp as somebody who has done the good deed without incurring the actual cost of doing that deed.
tldr: hobo in house is nono, it affects me. hobo in city is ok, it does not affect me, (maybe affects you).