They're calling you out on asking why the homeless don't just move, ignoring that (a) even the homeless have roots and social networks in the areas they live in, (b) long-distance travel is not trivial for those without financial means, (c) they may not have a reason to move away (what good is it to still be homeless in another town that you don't know?) and possibly other points.

Clearly, there are systemic reasons for certain ethnicities to be at higher risk of becoming homeless (not just in the U.S.). There are also clear reasons why people who share an ethnicity like living near each other, regardless of financial means. I think you're looking for a causation between two phenomena that may be entirely independent from each other.

Edit: I think this may have started with a misinterpretation of the initial post here (which was by a user who hasn't replied any further). You may have interpreted it as "in the Bay area, PoC are more likely to be homeless" while the original wording also allows for the interpretation of "PoC are more likely to be homeless, which e.g. is noticeable in the Bay area" that doesn't imply causation and is how I read the comment.