Just read this very interesting 1962 article on the practice, Confessions of a Blockbuster. The anonymous author of the article, a self-styled "blockbuster", lays out his MO as follows:
I make my money—quite a lot of it, incidentally—in three ways: (1) By beating down the prices I pay the white owners by stimulating their fear of what is to come; (2) by selling to the eager Negroes at inflated prices; and (3) by financing these purchases at what amounts to a very high rate of interest.
The crooked realtors were cheating white homeowners of a sizable portion of the equity in their homes, while turning around and bilking the black buyers with ruinous mortgages and interest schemes they could never hope to pay off. In effect, they were robbing whites and blacks of their life savings while contributing to urban blight and overcrowding. Why did city governments, segregationist homeowners' associations and liberals seeking to improve the lot of northern blacks never find common cause to root out the practice? Did any mayors, governors, or presidents between Truman and Reagan ever even acknowledge the problem or lay out a plan to deal with it?
Only indirectly related to block busting, but have you read the Kerner report? Was established by LBJ to investigate causes of urban riots. LBJ then decided he wasn't running, so many of its conclusions were never implemented.
More direct to your question, yes Nixon intervened to actually ignore the problem - by stopping his secretary of Housing and Urban Development from trying to fix urban housing issues. That secretary was George Romney, Mitt's father:
The plan, George Romney wrote in a confidential memo to aides, was to use his power as secretary of Housing and Urban Development to remake America's housing patterns, which he described as a "high-income white noose" around the black inner city.
The 1968 Fair Housing Act, passed months earlier in the tumultuous aftermath of the Rev. Martin Luther King Jr.'s assassination, directed the government to "affirmatively further" fair housing. Romney believed those words gave him the authority to pressure predominantly white communities to build more affordable housing and end discriminatory zoning practices.
Romney ordered HUD officials to reject applications for water, sewer and highway projects from cities and states where local policies fostered segregated housing.
He dubbed his initiative "Open Communities" and did not clear it with the White House. As word spread that HUD was turning down grants, Nixon's supporters in the South and in white Northern suburbs took their complaints directly to the president.
Nixon intervened immediately.
"Stop this one," Nixon scrawled in a note on a memo written by John Ehrlichman, his domestic policy chief.