HUD wouldn't be the ones to go after them. Per how the US Government works, the Department of Justice[1] would be the ones to go after the individuals involved. If you go to the DoJ website they have some very recent press releases on redlining prosecution, but I get the feeling it would take a while to figure out if any are related to Facebook ads (there search sucks).

1) https://www.justice.gov/usao/about-offices-united-states-att...

Raise the relevant budgets, hire a few thousand more US Attorneys and maybe they'll get around to it.