The fair housing act does not mention "socially marginalized groups". It says that it shall be unlawful
To discriminate against any person in the terms, conditions, or privileges of sale or rental of a dwelling, or in the provision of services or facilities in connection therewith, because of race, color, religion, sex, familial status, or national origin.
The U.S. Supreme Court just ruled on a case, Texas Department of Housing & Community Affairs v. The Inclusive Communities Project Inc., that covered disparate impact as a measurement of discrimination. Disparate impact raises the question of whether policies that appear to be neutral but result in a disproportionate impact on protected groups are legal.
The Supreme Court, in its ruling, indicated that disparate impact claims can be brought but it also imposed significant limitations.
How does this case apply to your question?
The underlying situation in the referenced case is one where, from the ruling:
The ICP alleged the Department has caused continued segregated housing patterns by its disproportionate allocation of the tax credits, granting too many credits for housing in predominantly black inner-city areas and too few in pre-dominantly white suburban neighborhoods.
The basis of the claim, which can now be heard under a disparate impact claim, is that a government organization discriminated against pre-dominantly white neighborhoods.
FHA protects against racial discrimination, not against racial discrimination only against certain groups.