I have absolutely been pressured to "reconsider" when I marked an intern in a diversity target group as a no-hire, and said intern was then switched into a different team.

EDIT 1: The more effective mechanism that my company uses is to verify at the time of hiring a candidate that you can show you at least considered diversity target candidates (in engineering, basically women and non-Indian/Asian/white).

EDIT 2: also definitely see diversity target group employees being flagged for second-look when identifying layoffs, PIPs etc.