So the subsidy argument falls apart. If it doesn't cost the city money overall and white people end up paying more both for housing and in taxes then the problem with redlining lies elsewhere. (I am not trying to defend redlining, by the way.)
So, no I don't think the subsidy argument falls apart.
You still have the problem that subsidies are generally thought to cost money. If redlining makes the city money it goes from "this is evil and doesn't work economically" to "this is evil but it makes money."
I'm starting to interpret the "don't complain about downvotes" guideline as "don't shed light on how this community misuses downvotes to quietly marginalize contrary views while maintaining the illusion of civil discourse."