No, not implicitly. That's why she started PP, explicitly to control the population of "oversexed" blacks.
Did she actually say “blacks” or did she use euphamisms like “those who are feeble-minded” or “undesirables” as a substitute?
I don’t doubt you are (ultimately) correct in her meaning, but I’m not aware of a (blatant) quote where she advocates for the control of the black (specific) population.